Two classic categories of a status of disqualification are that of the Shabbat violator and the heretic. Both categories require closer investigation. Shabbat violators have been excluded in the past primarily when their violation was part of a break with the community. Today, besides the arguments for decreased culpability based on tinok she’nishba, this reality does not exist: Shabbat violators do not stand outside the community, and this status of disqualification should not be relevant.
The status of the heretic was an innovation of Rambam, and it appears that even he did not apply it consistently. A close reading indicates that only heresy that leads to transgressive action translates into a status of disqualification. Hazon Ish goes further and implies that even without actual transgression, heretical beliefs can invalidate if it undermines the person’s felt religious reality of being under the “yoke of mitzvot.” In addition to those framings, many argue that tinok she’nishba and decreased culpability applies as much to the issue of heresy as to that of Shabbat violation. Today, another factor is relevant. Given that our beliefs must be affirmed and cannot be taken for granted as they were in the past, one who does not believe has not committed the rebellious act of heresy; he merely does not believe.
We conclude that a status of disqualification applies only in the case of 1) heretical beliefs that 2) translate into transgression 3) such that has the effect of setting a person outside the boundaries of his community. In today’s world, it is very hard to meet the criteria for 1 or 3, as a lack of belief is rarely if ever actual heresy and nonobservance of Shabbat is rarely if ever a full breaking away from the Jewish community. There may still be certain areas where such people cannot play active roles, and these must be explored further, both with regard to the rules that guide this and in looking at case-by-case requirements. As a matter of personal status, however, they would not be disqualified.
Opening: Basis for stam yaynam
Section 1: Status of a Shabbat violator
Part 1: Rishonim and Poskim
Part 2: Historical Development and Conclusion
Section 2: Status of one who does not believe
Part 3: Gemara and Rambam
Part 4: Understanding Rambam
Part 5: Different Types of Heresy and Applications for Today
2.4.1. An apikores cannot be a shochet
There is, however, one other area, in addition to testimony, where Rambam rules that a heretic has a status of disqualification, and that is the case of ritual slaughter. He states:
|ישראל משומד לעבירה מן העבירות שהיה מומחה הרי זה שוחט לכתחלה… ואם היה משומד לעבודה זרה או מחלל שבת בפרהסיא או מין והוא הכופר בתורה ובמשה רבינו כמו שביארנו בהלכות תשובה הרי הוא כגוי ושחיטתו נבלה||A Jew who is a meshumad regarding a particular sin, who is an expert in ritual slaughter, such a person may slaughter ab initio…. And if he was a meshumad regarding the worship of foreign gods, or if he was a public Shabbat violator, or a min, that is one who is a denier of Torah and Moshe our Teacher, as we explained in the Laws of Repentance, such a person is like a non-Jew and his slaughtered animals are non-kosher carcasses (Laws of Shechita, 4:14).|
Here, then, is a case outside of the laws of testimony where, according to Rambam, a heretic’s status is “like a non-Jew.” It is true that this ruling may be only rabbinic, as even the invalidity of a non-Jew, provided he is not an idolater, may only be rabbinic according to Rambam (see 4:12, and Kesef Mishneh, ad. loc.). Nevertheless, the point still stands: a heretic is given a status of disqualification; he is “like a non-Jew.”
However, the complicated nature of the matter is revealed two halakhot later (4:16):
|אלו הצדוקין והבייתוסין ותלמידיהן וכל הטועים אחריהן שאינן מאמינים בתורה שבעל פה שחיטתן אסורה, ואם שחטו בפנינו הרי זו מותרת, שאין איסור שחיטתן אלא שמא יקלקלו והם אינן מאמינין בתורת השחיטה לפיכך אינן נאמנין לומר לא קלקלנו||These Sadducees and the Beitusim and their students and all those who follow them who do not believe in the Oral Torah, their slaughtering is forbidden. If, however, they slaughtered in our presence, it is permissible, for the prohibition regarding their slaughtering is only due to a concern that they slaughtered incorrectly, and they do not believe in the rules of ritual slaughtering and hence they are not trusted to say that they did not do it incorrectly.|
According to this ruling, one need not believe in the laws of shechita to be a valid shochet (it is different in this way from what we saw regarding the laws of eruv). Thus, a Sadducee can be a shochet as long as we know that he performed the shechita correctly. What is not clear is why he does not have the same status as the heretic, who is considered to be “like a non-Jew” and excluded on the basis of his personal status. Since Sadducees reject the Oral Law, they should also be deemed to be heretics, as Rambam himself rules in Laws of Repentance (3:8):
|שלשה הן הכופרים בתורה: האומר שאין התורה מעם ה’ אפילו פסוק אחד אפילו תיבה אחת אם אמר משה אמרו מפי עצמו הרי זה כופר בתורה, וכן הכופר בפרושה והוא תורה שבעל פה והמכחיש מגידיה כגון צדוק ובייתוס…||Three are described as kofrim ba’Torah, “who denies the Torah”: 1) One who says that Torah is not from God. Even if he says that one verse or one word, Moses said on his own, he is denying the Torah. 2) One who denies the interpretation of the Torah, which is the Oral Law, or disputes [the authority of] its spokesmen as did Tzadok and Beitus…|
If both Sadducees and those who deny the Written Torah fall into the same category of “deniers of Torah,” how are we to understand why a Sadducee can be a shochet if one who denies the Written Torah cannot?
The answer to this question is critical for our understanding of the scope of the exclusion of a heretic according to Rambam. As we have seen, such a person’s exclusion from being a shochet is the only place other than testimony where Rambam excludes non-believers. Later poskim who rule that an apikores has a status of disqualification do so because they are following Rambam’s lead. By exploring why Rambam excludes minim from the role of a shochet but includes Sadducees, we will be able to understand what type of non-believer is excluded by Rambam and what type is not.
It seems that the key difference is between a heresy that leads to action and one that does not. It is to this distinction we now turn, one I will develop at some length. After this discussion, we will turn to the question of “heresy in our days,” much in the way we looked at the special standing of “Shabbat violation in our days.” In that section we will explore whether there is a difference between the heresy of old and the lack of faith of today, either due to decreased culpability or because the nature of the heresy is different.
2.4.2. Heresy that leads to action and heresy that does not lead to action
In explaining why a Sadducee can be a shochet if one who does not believe in the Written Torah cannot, there are those who state that the heresy of not believing in the Oral Torah is less severe than the heresy of not believing in the Written Torah. Nevertheless, it seems that a mere explanation of “degree” falls short. There must be something substantive that stands behind these different heresies and explains this difference.
The answer, it would seem, is already indicated in Rambam’s ruling in Laws of Eruvin (2:16):
|אבל אם היה מן המינים שאין עובדין עבודה זרה ואין מחללין שבת כגון צדוקין וביתוסין וכל הכופרים בתורה שבעל פה… שאינו כגוי||But if he were one of the heretics that do not worship foreign gods and that do not violate Shabbat, like the Sadducees and the Beitusim, and all those who reject the Oral Torah…. then he is not considered to be as a non-Jew.|
For Rambam, the reason Sadducees do not have the status of “like a non-Jew” is not because their heresy is less severe as heresy than that of, say, someone who denies the Written Torah. Rather, it is because this heresy does not entail the violation of Shabbat. The assumption here is that the heretic will act on the logical consequences of his beliefs. Thus, a heretic who still believes in the Written Torah is a heretic who keeps Shabbat, and thus he is not like a non-Jew. In contrast, a heretic who denies the Written Torah is someone who will act on his beliefs and thus violate Shabbat. It is for this reason that such a heretic is invalid as a ritual slaughterer.
That Rambam assumed that a person’s heresy would translate into his actions can be seen in what he writes in the Laws of Idolatry (2:5):
|וכן המינים מישראל אינן כישראל לדבר מן הדברים ואין מקבלים אותן בתשובה לעולם… והמינים הם התרים אחר מחשבות לבם בסכלות דברים שאמרנו עד שנמצאו עוברים על גופי תורה להכעיס בשאט בנפש ביד רמה ואומרין שאין בזה עון…||Similarly regarding Jewish heretics, they are not like Jews in any matter, and we do not accept them in repentance ever….And the heretics are those who stray after the thoughts of their hearts concerning themselves with foolish matters as we have said, until they ultimately transgress the body of the Law arrogantly with scorn, to provoke God’s anger, and they say that there is no sin in this…|
It is clear that, for Rambam, a heretic will act on his heresy, and this is part of why he is so dangerous.
In his Commentary to the Mishna (Hullin, 1:2) as well, Rambam emphasizes that the false beliefs of minim lead them to sin. Significantly, the context here is a discussion of who is a min to be invalid as a shochet. He writes:
|ומינים אצל חכמים הם הכופרים מישראל… והם בני אדם אשר טמטמה הסכלות את שכלם והחשיכו התאוות את נפשם ופקפקו בתורה ובנביאים עליהם השלום מתוך סכלותם, ומכחישים את הנביאים במה שאין להם בו ידיעה, ועוזבים את המצות מתוך זלזול, והכת הזו היא כת של ישוע הנצרי ודואג ואחיתופל וגחזי ואלישע אחר וכל ההולך בשטתם שם רשעים ירקב. ויוודע שהאדם מן הכת הזו כגון שנראה מתבטל ממצוה מן המצות מתוך זלזול בלי שישיג באותו המעשה הנאה האנשים הללו אשר זה תיאורם אסור לאכל משחיטתם, וכך אמרו תנו רבנן שחיטת מין לעבודה זרה פתו פת כותי יינו יין נסך ספריו ספרי קוסמים פירותיו טבלים בניו ממזרים||The minim that the Sages referred to are the heretics from Israel….and they are people whose intellect has been corrupted by foolishness, and their desires have darkened their souls, and they have raised doubts regarding the Torah and the prophets, peace be upon them, due to their foolishness. And they deny the prophets regarding matters which they have no knowledge about, and they abandon the mitzvot out of contempt. This is the sect of Jesus of Nazareth and Doag and Achitophel and Geichazi and Elisha-Acher, and all who follow their approach, may the name of the wicked rot. And it can be known that a person is from this sect if he is seen not performing a mitzvah of the mitzvot out of contempt, without gaining any pleasure from the act. Regarding these people, for whom this describes them, it is forbidden to eat from their slaughter, and so they (the Rabbis) said: “Our Rabbis have taught: the slaughtering of a min is intended for idolatry, his bread is the bread of Samaritans, his wine is yayin nesekh, his scrolls are the books of soothsayers, his fruit is untithed and his children are mamzerim (Hullin, 13a).|
Rambam repeats here time and again how the min is not just someone with wrong beliefs; he is someone who sins as a result of his heresy and does so contemptuously. In fact, the way a person can be identified as a min is through his actions, when he is seen sinning in a way that reflects his heresy.
Rambam also characterizes such a person as someone who is part of a sect, not just an individual with certain beliefs or actions. Clearly, then, we are talking about someone whose heresy has led to action and who, in his practice, has not just sinned but broken away from the community. This is reflected in the halakhic treatment of him as someone who is completely outside the community—his wine, bread, meat, and children—all of these are forbidden. He is someone who, in other words, is seen as a non-Jew. 
Consistent with this, in his responsum on Karaites, after stating that their heresy related to less core areas of faith than those of the class minim, Rambam states, כל אימת דלא פקרי בחציפותא לא חשבינן להו כוותיהו, “as long as they do not mock and deride, we do not consider them as minim.” What, we can ask, is the relevance of their mocking and deriding to their classification as minim? This is further evidence that this classification is not just about heresy, per se, but about the ways that heresy puts a person outside of the community. This is the real difference between those who reject the Written Torah and those who reject the Oral Torah. The former violate Shabbat and act in ways that put them outside the community. This does not hold true about for latter group as long as, Rambam adds, they do not set themselves apart from the community through their mocking and deriding of its beliefs and its religious leaders.
In short, due to the higher standards required for a person to serve as a witness, Rambam categorically disqualifies a person with heretical beliefs from this role, but from this only. The one other case where the issue of status disqualification arises is in the laws of ritual slaughter, but the comparison to the case of Sadducees demonstrates that it is not the heresy per se that invalidates such a person. Rather, a person whose heresy has or will entail Shabbat violation is invalid; one whose heresy will not do so remains valid.
This parallels what we saw earlier regarding Shabbat violation. There, we saw that a number of important poskim ruled that Shabbat violation itself would not invalidate a person unless it was in a context of a true breaking away from the community. Here, we are seeing that heresy does not invalidate unless it leads to such actions as Shabbat violation, actions that would put a person outside of the community. We return then to the three-part criteria we delineated above according to Rav Ettlinger and Rav David Zvi Hoffmann. Giving someone a status of disqualification requires 1) heretical beliefs that 2) translate into transgression 3) such that has the effect of setting a person outside the boundaries of his community.
Effectively, then, the only apikores that has a halakhic status of disqualification outside the realm of testimony would be one that essentially is the same as the mumar li’hakhis, the person who sins to provoke God’s anger, that is, someone who sins as a matter of principle. The only difference might be that the mumar li’hakhis does not have a religious or philosophical system that he subscribes to; he is just alienated and does not believe or see himself to be obligated. The apikores, on the other hand, subscribes to a philosophy which leads him to conclude that he need not observe the mitzvot. The mumar starts with his actions; the apikores starts with his beliefs. But it both cases it is the marriage of the two, belief and action, that determine his status.
Even for Rambam, then, in the area of practical halakha (as opposed to protecting the community from the dangers of heresy or matters of the World to Come), and with the exception of laws of testimony, what matters in the end is action or belief that will lead to action, not belief itself.
2.4.3 Hazon Ish: belief that underpins obligation
I am not the first to make this type of argument. Hazon Ish (YD, 2.18) also explains Rambam this way:
|ואפשר דכופרים נלמד ממחלל שבת בפרהסיא או מומר לכה”ת כולה דאפ’ לתיאבון הן בכלל מומרים לכה”ת כולה מפני שפרקו עול תורה מעל צוארם כל שכן הכופר שאין לו חלק בתורת משה שאם אין אמונה אין כלום…
וחטא הכפירה עצמה הוי כחוטא להכעיס שענין להכעיס היינו שמשריש בקרבו התנגדות לשמירת מצוה מן המצוות וכש”כ כשמשריש בקרבו כפירה…
|It is possible that Rambam derived the status of heretics from that of the public desecrator of Shabbat or one who violates the entire Torah, for even when their actions are due to desire (and not principled rejection), they are considered as mumrim for the entire Torah, since such people have cast off the yoke of Torah from their necks. Certainly then, one who rejects [core principles of faith] has no portion in the Torah of Moshe, since without faith there is nothing…
And the sin of heresy itself is like one sinning to provoke God, because the principle behind the category of “sinning to provoke God” is that one inculcates inside oneself defiance to the observance of a mitzvah from among the mitzvot, and this is certainly the case when one inculcates inside oneself heresy…
According to Hazon Ish, the reason a mumar has a status of disqualification is because his actions have the effect of inculcating in him a belief that he is free from the yoke of the mitzvot. This, says Hazon Ish, is why the heretic has a similar status; his heresy also allows him to feel free from the yoke of mitzvot. A person’s self-perceived sense of obligation requires the religious belief that undergirds such obligation. What is core here is not belief per se, but belief as a necessary component of felt religious obligation. Whether through action such as Shabbat violation or through heresy, a person has a status of disqualification when he does not see himself as obligated in mitzvot. 
This, then, explains why a Sadducee can be a shochet:
|והמכחיש תורה שבע”פ ומתעמל לקיים תורה שבכתב כפי דעתו לענין מורידין דינו כמומר שהרי חטא זה הוא כחטא להכעיס וכמש”כ לעיל, וכש”כ שיש בכפירה זו עקירת כמה איסורים שבתורה ואמנם מקרי בר זביחה אם שומר שחיטה כהלכתה||Now one who denies the Oral Law but exerts himself to fulfil the Written Law according to his understanding, when it comes to the law of bringing about such a person’s demise, he is to be treated as a mumar, since this is like a sin that is intended to provoke God’s anger, as we have written above, and how much more so is this true when the heresy leads to the uprooting of a number of prohibitions in the Torah. Nevertheless, such a person is considered to be a bar zevicha (in the category or ritual slaughter), if he observes shechita according to all its laws.|
For Hazon Ish, the Sadducee or Karaite may be a heretic worthy of the judgment of moridim. Nevertheless, because he believes in the Written Law, he still sees himself as obligated in mitzvot. A key word in this passage is מתעמל, that this person exerts effort in the fulfillment of the mitzvot, showing that he genuinely sees himself as obligated. His heresy does not have the effect of taking him out of the realm of obligation. He believes in a Commander and he believes in the commandments. What he does not believe in are some of the specifics regarding the commandments. While that is a heresy, it is not a heresy that leads to a fundamental breaking away from the yoke of mitzvot or from the community committed to mitzvot.
This is the core difference between the lack of belief in the Oral Law and the lack of belief in the Written Law. In the first case, there is still a belief in the mitzvot. In the second case, there is not. Similarly, if someone did not believe in the resurrection of the dead, or in mashiach, he would not be disqualified as this heresy would not undermine the psychological reality of the “yoke of mitzvot.”
There is a central question that needs to be answered according to this approach. What would be the status of someone who did not believe in the Written Torah, or who did not even believe in God, yet still believed himself to be obligated in the mitzvot? While this sounds strange, there are definitely people in this category, people who see themselves as obligated by history or by their link to the Jewish people. Would such a person have a status of disqualification, or would such a belief be sufficient to create the reality of being under the yoke of mitzvot?
It would seem from what Hazon Ish writes elsewhere in a discussion of conversion that, for Hazon Ish, such a belief would not suffice, at least not for a convert who needs to accept the yoke of mitzvot to enter the faith. For a prospective convert, only a belief in God Who commanded the mitzvot can be said to create the psychological reality of what it means to accept the yoke of mitzvot. While he does not make a similar statement explicitly in his discussion about a Jew who commits heresy, it stands to reason that Hazon Ish would rule similarly and state that such a person could in no way be seen to be under the yoke of mitzvot.
One could, however, distinguish between the two cases and argue that to take oneself out of the yoke of mitzvot requires a more complete rejection. According to this, as long as someone who genuinely is obligated continues to believe himself to be obligated, for whatever reason, then he would not be given a status of disqualification.
Many people, however, and probably more than we are willing to recognize or admit, are fully committed to a life of mitzvot, and yet do not see themselves as obligated. What would be their status?
Rambam’s formulations emphasize whether the person is actually living a life of observance or transgression. Following this, such a person would not have a status of disqualification. Hazon Ish, on the other hand, focuses on the need for felt religious obligation. According to him, it seems that such a person would have such a status.
To conclude this section, we have seen that Rambam rules that a person who has heretical beliefs is a min or apikores, and that he has a status of disqualification. Nevertheless, closer analysis demonstrates that Rambam would only rule this way when such belief led to transgressive action, perhaps only action that actually set the person outside the community. According to this, if a person doesn’t believe but fully observes, he would not have a status of disqualification. A more limited approach emerging from Hazon Ish would say that observance of mitzvot does not suffice unless it is informed by a person’s belief in their obligation. What such belief exactly consists of remains somewhat unclear.
Such a distinction has to contend with the fact that Rambam groups the two together in Laws of Repentance (3:8). Thus, while Lechem Mishne (Laws of Shechita, 4:11) suggests this distinction, he cannot understand why it should matter: מכל מקום מאין מצא חילוק זה לענין שחיטה, וצ”ע.
Nevertheless, Rambam, in the teshuva regarding Karaites quoted earlier, seems to do exactly this, namely, to distinguish between more severe and less severe forms of heresy:
ואם נפש אדם לומר האי דר’ טרפון דאיתיה במסכת שבת בפרק כל כתבי הקדש דתנן ר’ טרפון אומר… שאפי’ רדף רודף אחריו להורגו ורץ נחש אחריו לנשכו אל יכנס בבתיהם אפי’ בשעת הסכנה כל שכן ללכת לשאול להם לשלום שלא בשעת הסכנה האי לא קשיא מידי דהנהו מילי דר’ טרפון במינים דכפרי בעיקר נינהו ודמו להנהו דדרשי בהו חכמי’ הרחק מעליה דרכך ואל תקרב אל פתח ביתה זו המינות והרשות ודמיאן להנהו דאיתמר עליהוי המינים והמשומדים מורידין ולא מעלין אבל הני דהכא כל אימת דלא פקרי בחציפותא לא חשבינן להו כוותיהו ופלגינן להו יקרה ומלינן לבנייהו בשבתא
On the face of it, it seems that Rambam is distinguishing between more severe heresy—denying God—and less severe heresy—denying the Oral Torah—and only those in the first category have a status of disqualification. A person who denies God, it should be noted, is categorized by Rambam in Laws of Repentance as an apikores, a category of a more fundamental heresy than that of kofer ba’Torah. If we were to apply this hierarchy to Rambam’s ruling in the Laws of Shechita, we would have to say that those who deny the Written Torah are in the category of the more severe heresy, and those who deny the Oral Torah are in the category of the less severe heresy, although both fall in the same category of kofrim ba’Torah.
This seems to be echoed in another responsum (no. 263):
ואלה הקראים אינם אלה אשר קורין אותם החכמים מינים, אלא קורין אותם צדוקין וביתוסין להוציא הכותים והמינים הם אשר נתפסדו להם האמונות בעיקרי התורה, ומכללם האומרים אין תורה מן השמים וכבר ביארו, שאין הפרש בין המכחיש התורה כולה או מכחיש פסוק אחד ואומר משה מפי עצמו אמרו
According to this passage, rejecting the Written Torah makes someone a min; rejecting the Oral Torah does not. The Karaites, whom Rambam identifies halakhically with the Sadducees of the Talmud, are lesser heretics because they only deny the Oral Torah and not the Written Torah.
The problem with this answer is that first, as stated, Rambam puts these two in the same category in Laws of Repentance. More to the point, in Mishne Torah he explicitly includes those who deny the Oral Torah in the category of the people whom are to be thrown down the pit:
מי שאינו מודה בתורה שבעל פה אינו זקן ממרא האמור בתורה, אלא הרי זה בכלל המינים ומיתתו בכל אדם. מאחר שנתפרסם שהוא כופר בתורה שבעל פה מורידין אותו ולא מעלין והרי הוא כשאר כל המינים והאפיקורוסין והאומרין אין תורה מן השמים והמוסרין והמשומדים, שכל אלו אינם בכלל ישראל ואין צריך לא לעדים ולא התראה ולא דיינים אלא כל ההורג אחד מהן עשה מצוה גדולה והסיר המכשול
It is not enough to posit that one heresy is more severe than the other without seeking the reason that would lead to this distinction. Why, when it comes to categorizing them in the Laws of Repentance and to throwing them down the well are they in the same category, while when it comes to being a shochet they are treated differently? We must find that which stands behind this difference and would explain the reason for these different rulings.
Later in his Mishna Commentary, Rambam also invalidates the shechita of the Sadducees against his ruling in Laws of Shechita. To reconcile these, we could posit that he is only invalidating their shechita due to a concern that it was not performed properly in the technical sense. He also states in his Mishna Commentary that Sadducees are commonly referred to as minim although they are not technically such. This parallels his ruling in Laws of Shechita that they are a separate class of minim, ruling there that, as such, their shechita is valid.
In his discussion of conversion, Hazon Ish similarly raises the importance of belief as a component of conversion, a matter not discussed directly in the Gemara. Although he requires proper belief, for him what is important is belief that defines what it means to be obligated in mitzvot, not belief as a per se requirement:
ונראה דענין גירות אינו אלא למאמין ביסודו שצוה ד׳ את ישראל חקים ומשפטים ע״י משה נביאו והבדילה מכל העמים ומסר להם כי יכולים לקבל גרים מכל העמים ע״י מילה וטבילה וקבלה, והנה נכנס לזה לתורת עם הישראלי לכל דורותיו עד העולם, אבל אם אינו מאמין בכל זאת אלא שמקבל עליו להתנהג ע״פ חקי התורה מפני שההנהגה הזאת מטיבה אותו או מצלת אותו מן ההיזק אין זה קבלת גירות, וכדאמרינן יבמות [מ”ז א’] והוי יודע עד שלא באת למדה זו אכלה חלב אי אתה ענוש כרת…
“It appears that conversion is only for one who believes in the principle that God command Israel in the edicts and the laws through Moshe His prophet, and separated them from all the nations and transmitted to them that they are able to accept converts from the other nations through circumcision and immersion and the acceptance of mitzvot, and that such a person enters into the Israel people for all generations, forever. But if one does not believe in all this, but rather accepts upon himself to practice according to the laws of the Torah because such a practice is good for him, or saves him from injury, such is not the acceptance of conversion. As they say: ‘Know that before having entered into this state were you to eat forbidden fat you would not be deserving of karet.’” (Hazon Ish, YD, 119.2).
Although he presents here a number of necessary beliefs, it is clear that they are all to one goal: to make the person’s acceptance of mitzvot one of religious obligation and not one of a mere commitment to a set of practices. It is accepting the yoke of mitzvot, not the lifestyle of mitzvot. He demonstrates this by the Gemara’s presenting of the laws of kashrut together with the religious consequence of violating those laws (karet for forbidden fat). Only when such belief is the context and the background can there be a true acceptance of mitzvot.
I thank Rabbi Yaakov Love for helping me think through this point.
See his ruling, quoted above, regarding the belief necessary for the act of conversion (Hazon Ish, YD, 119.2).
It is interesting to compare the Talmud’s discussions regarding the convert with those regarding the mumar. So, for example, there is an issue with a mumar li’davar echad, a mumar in regards to one matter, and an issue with a convert who accepts all of the mitzvot chutz mi’davar echad, with the exception of one matter. This parallel is also present in Sifra, ch. 2, s.v. Adam.