The traditionalist Jewish community does not live in isolation. Even among those who seclude themselves and restrict their interaction with “outsiders,” there is still a necessary reaction to the practices of others. Perhaps the most famous example was the removal of the ten commandments from the daily liturgy so as not to unintentionally support the heresies of those who claimed that only these laws are binding. Similarly, the addition of the blessing against “informers” was certainly a response against sectarians. More recently, the Vilna Gaon’s abolition of the custom to decorate synagogues with trees on Shavuot reflects a reaction to Gentile religious practice. These few examples, and there are many more, demonstrate an awareness of external developments and a need to adjust normative practice to accurately reflect old distinctions in a new reality. Additionally, any proposed innovation must be weighed within the inverse of this scale. We must carefully consider not only its internal implications but also its repercussions outside of our proverbial ghetto walls.
The primary consideration is certainly the biblical prohibition against following the ways of the Gentiles. This is a highly nuanced commandment that is widely discussed in the halakhic literature. Another issue that reflects the impact of external practice on internal developments and also the potential effect of internal custom on external parties is the less famous, although certainly worthy of consideration, prohibition against imitating heretics and thereby encouraging them in their deviant ways. Out of a sensitive concern for their fates and a desire to not even slightly worsen their position vis a vis traditional Judaism, we must carefully ensure not to strengthen any of their misperceptions.
The Mishnah in Hullin (41a-b) records:
One may not slaughter at all into a pit. Yet, one may dig a pit in one’s own house for the blood to run into. In the street, however, one should not do so lest one confirm the sectarians (minim) in their ways.
The Mishnah here is somewhat unclear. It first states that one may not slaughter and have the blood fall into a pit. This is either because sectarians used this method in order to collect blood for their idolatrous sacrifices or because they collected blood in this way to eat in their pagan services. According to both opinions, this otherwise permissible method of slaughtering is prohibited because of idolatrous sectarian practice; because what is done outside of our community affects what may be done within it.
However, the Mishnah continues to permit the practice in one’s house but not in the street, which seems to directly contradict the immediately preceding prohibition. In the Gemara (41b), Rava authoritatively explains the Mishnah’s language as meaning that slaughtering directly into a pit is forbidden everywhere but slaughtering into a ditch that allows the blood to drip into a nearby pit is permitted in one’s house but not in the street. A baraita is brought to confirm Rava’s distinction and this baraita attaches to the prohibition against slaughtering in this way the verse “You shall not walk in their ways” (Lev. 18:3), the source for the prohibition against following Gentile practices.
The simple way to understand this passage is that these are all examples of idolatrous practices that we may not follow, consistent with the prohibition against “walk[ing] in their ways.” However, Rashi explains differently. As indicated above in our translation of the Mishnah, Rashi writes that slaughtering into a ditch that leads to a pit is prohibited because it will confirm the sectarians in their ways (yahazik yedeihem be-hukoteihem). According to him, the prohibition involved in this matter is not one of following prohibited idolatrous practices but of imitating sectarian practice. Rashi explains that one may not slaughter into a pit, “even in [one’s] home because it looks like a sectarian practice.” Even when the prohibition against following Gentile or idolatrous practice no longer applies, we are still prohibited from appearing to follow sectarian practice so as not to strengthen their resolve and confirm their position.
Rambam has a different way of understanding this issue. In explaining the prohibition against slaughtering into a pit he writes, “because this is the practice of idolaters.” This is Rambam’s explanatory addition to the Mishnaic passage. Rather than maintaining the Mishnah’s explanation of “lest he confirm the sectarians in their ways,” Rambam offered his own explanation that seems to invoke the baraita’s citation of “You shall not walk in their ways” (Lev. 18:3). This was in regard to slaughtering directly into a pit. However, in describing the prohibition against slaughtering into a ditch that drips into a pit, Rambam reverts to the Mishnah’s “lest he confirm the sectarians in their ways.”  Evidently, according to Rambam sectarians only slaughter directly into pits and, therefore, only this is considered to be a prohibited idolatrous practice. However, while slaughtering into a ditch that leads to a pit is not technically an idolatrous practice, it is a practice that conforms to sectarian rules and, therefore, gives the appearance of trying to follow sectarian regulations. This alone, appearing to intentionally obey sectarian rules, is prohibited because it strengthens their resolve. When they see another person coming closer to their practices it legitimates them and reinforces their position.
This can be further seen from the exception to the general rule that the day following a holiday – is’ru hag – has a special status that includes a prohibition against eulogizing and fasting. The Mishnah in Hagigah (2:4) states that when Shavuot falls out on Shabbat, the next day, Sunday, is not given any unusual practices. The reason for this exception is that Second Commonwealth sectarians always observed Shavuot on the Sunday following the traditional Shavuot. Because observing a semi-festive day on the Sunday following Shavuot might be seen as partial agreement with sectarians, it is not practiced even though it would otherwise be required. We must not strengthen the position of sectarians even to the point of omitting a rabbinically ordained observance.
The source for this prohibition is, presumably, the Mishnah and Gemara in Gittin (61a, 62a) that one may not encourage sinners in their incorrect ways. Even a mere verbal greeting that could be understood as encouragement is rabbinically forbidden. It stands to reason that active encouragement, including imitation, would also be prohibited, as discussed above.
From all the above, and particularly Rashi’s explicit statement in Hullin, we see a prohibition against observing sectarian practice if it will strengthen the public stature of sectarianism. The application of this prohibition to modern heterodox movements seems self-evident. While the sectarianism referred to in the Mishnah was idolatrous, there is no indication that idolatry per se is a necessary requirement for falling under this prohibition. It is well established among historians that the term sectarian (min) refers to a broad category of deviants and, as R. Samson Raphael Hirsch expertly demonstrated in his open debate with R. Seligman Baer Bamburger regarding Austritt, within the Maimonidean framework the term certainly applies to heterodox movements. If so, and, as we shall see, numerous halakhic authorities have affirmed this, there is a prohibition against embracing heterodox practices when and if such adoption confirms the heterodox in their ways. What remains to be determined is what can be considered sufficient confirmation to be prohibited.
The first modern halakhist that this author was able to find who applied this passage in practice was the great authority R. Moshe Sofer, the famed Hatam Sofer. Perhaps surprisingly, his utilization of this prohibition was not in the form of a polemic but as part of a responsum to a traditional rabbi who had requested guidance in planning the doors and outer hallway of a new synagogue. The doors to the actual sanctuary must be in the west but, the respondent asked, is there any rule about the doors leading from the outside into the hall? After thoroughly analyzing this obscure topic, R. Sofer added that since Reform synagogues are built with the outer doors in the west, it is forbidden for a traditional synagogue to do likewise and, thereby, imitate the Reform.
However, since R. Sofer is known as having taken an extremely strong stand against Reform some discount his rulings on related issues. While this author shudders at the thought of dismissing this venerable authority, since others have less hesitance to do so this essay will focus on authorities generally considered more tolerant of others who are different and of innovative ideas.
R. David Tzvi Hoffman
The introduction of the organ into the synagogue was one of the earliest Reform innovations in the second decade of the nineteenth century and was roundly denounced in the 1819 collection of responsa from the leading rabbis of Europe titled Eileh Divrei ha-Berit. However, even clear directives from such luminaries as R. Akiva Eiger and R. Moshe Sofer would not deter the budding Reform movement. They had received the permissive rulings they desired, responsa from relatively unknown rabbis that had been previously published in the 1818 book Nogah ha-Tzedek, and no amount of scholarship or rabbinic presssure would deter them.
In 1897, long after Reform had come to dominate German Judaism and Orthodoxy, through the tremendous efforts of R. Samson Raphael Hirsch, R. Azriel Hildesheimer and others, had reasserted itself as a viable minority, the question was presented to R. David Tzvi Hoffman whether an Orthodox synagogue may use an organ during the week. In a monumental responsum, the man who later became the foremost halakhic authority in Western Europe neatly summarized the existing literature on the subject and then formulated his own extensive reasoning as to why an organ is prohibited in the synagogue even during the week. He received approval for his work from R. Azriel Hildesheimer and all but one of the rabbinic authorities he consulted. In addition to the prohibition against walking in Gentile ways, which he thoroughly analyzed from all positions, R. Hoffman also cited the prohibition against imitation, and thereby encouragement, of sectarians. Since the Reform movement certainly qualifies as sectarian, we may not adopt any of their practices which might confirm them in their ways. Once we take a small step towards Reform the public might think that, despite our protests to the contrary, this is only the first of many steps. This is not merely the concern of a dominant majority worried about the potential growth of a small deviant group for, as we have seen, this prohibition was invoked by R. Hoffman long after Reform had become dominant and a healthy Orthodox opposition had become established.
In the summer of 1935, the issue of an organ in the synagogue was brought before the world-renowned Chief Rabbi Avraham Yitzchak Kook. Evidently, a Sephardic rabbi in Israel had permitted the use of an organ, claiming that all of the previous rulings issued only apply to Ashkenazim. The matter was taken to Rav Kook who, without citing R. Hoffman’s recently published responsum which he may not have seen, arrived at the same conclusion that even if an organ were not a prohibited Gentile practice it would still be forbidden as a sectarian practice.
Rav Kook further cited this prohibition in 1938 regarding cremation. In addition to the obligations to respect and bury a deceased person, about which he wrote at length, Rav Kook further noted that since Reform had accepted cremation as an option it is forbidden to accept or even assist with this sectarian practice. If we are not allowed to encourage their practices through imitation, he argued, certainly the Orthodox “Hevra Kadisha” may not facilitate the Reform practice of cremation.
There is no question that in attempting to understand Rav Kook’s approach to the heterodox we must take much more into account â€“ his love for all Jews and, more generally, all people, his attitude towards the unlearned and non-religious, his approach to pluralism and on cooperation with those with whom he disagreed, his eschatological views, and more. This certainly applies also to R. Hoffman and all the other authorities cited here. However, our focus in this essay is a narrow halakhic issue that will admittedly give us an incomplete picture but one that is still necessary.
A few years after Rav Kook’s response, in late 1945, his successor as Chief Rabbi of Israel, R. Yitzhak Isaac Herzog, utilized this prohibition in response to a timely question. Less than two years before the United Nations approved a Jewish state in Israel, Rav Herzog was asked whether an Ashkenazi may adopt a Sephardic, or more likely Modern, pronunciation of Hebrew for praying. While the respondent, R. Levi Rabinowitz, lived in Johannesburg, South Africa, this was certainly a relevant question in the burgeoning community of ingathered exiles in Israel. Responding to R. Rabinowitz’s specific situation in Johannesburg, Rav Herzog wrote that since Reform in that location had grown and was utilizing Sephardic pronunciation of Hebrew, it was forbidden for R. Rabinowitz to change his pronunciation because it would appear to be an imitation of Reform practice which, as we have seen, is prohibited. This was not a “public policy” decision that it would be best not to change pronunciations. Rather, it was an outright prohibition based on the above issue and the realities of Johannesburg at the time.
R. Yehiel Ya’akov Weinberg
R. Yehiel Ya’akov Weinberg, the famed Lithuanian genius who grew to become the leader of pre-war German Jewry, cites this prohibition in three separate responsa. In one responsum he responded to the question of whether an organ may be used in a ceremony to inaugurate a new Jewish cemetery. Citing both the prohibition against adopting Gentile practices and that against imitating sectarian, R. Weinberg clearly distinguished between the two and argued that both applied in that situation. Explicitly affirming R. Hoffman’s approach, R. Weinberg wrote:
If we allow the use of musical instruments at the inauguration of a cemetery, the unlearned and unlettered will say, “The Pharisaic sages have permitted the matter.” It is therefore incumbent upon us to preserve our ancestors’ actions and not to deviate from their customs by even a hair’s breadth.
In a responsum from 1936, R. Weinberg addressed the issue of planting flowers on a grave. After considering all the possible objections, R. Weinberg concluded that this would be permissible except that, since Reform had previously adopted the practice, for the Orthodox to then adopt it would be a prohibited acceptance of a sectarian observance. Since we may not encourage them or lend credence to their practices, we must carefully avoid any innovations they may have initiated, even those that otherwise conform to halakhah.
In a third and oft-quoted responsum, R. Weinberg answered an inquiry about whether the celebration of a Bat Mitzvah is permitted. His main concern was that it might be considered a variation of the Christian confirmation ceremony, an issue he exhaustively analyzed and put to rest. However, a matter that he did not and could not dismiss was that the Bat Mitzvah ceremony was a heterodox innovation and, as such, may not be adopted. Imitating a heterodox practice, even if unintentionally, “has within it the strengthening of the destroyers because they were the first to initiate the new practice of celebrating the Bat Mitzvah.” This, R. Weinberg rules, is a sufficient reason to prohibit the Bat Mitzvah celebration. The only way for such a practice to be permitted is to sufficiently differentiate it from the heterodox celebration. Basing himself on the view of Tosafot, R. Weinberg argued that if it is obvious to onlookers that the ceremony is for a different reason than a corresponding heterodox ceremony would be for then it is permissible. The heterodox Bat Mitzvah is a dry synagogue ritual followed by a party for its own sake; the Orthodox Bat Mitzvah that R. Weinberg permitted is a celebration, specifically outside of the synagogue, of family joy and, more importantly, a time of educational strengthening of the religious development of a budding woman. As R. Weinberg quickly noted, those who do not utilize the opportunity properly and wish merely to have a party like those in the heterodox community have no halakhic permission to do so.
 Berakhot 12a
 Berakhot 28b-29a. Cf. Lawrence H. Schiffman, Who Was A Jew? (Hoboken, NJ: 1985), p. 53 ff.
 R. Avraham Danzig, Hayei Adam, 131:13. Whether the Vilna Gaon abolished only the custom about trees or also about flowers, see R. Yosef Levy, Minhag Yisrael Torah, vol. 2 p. 364.
 Cf. Shulhan Arukh, Yoreh Deah 178 and commentators; Encyclopedia Talmudit, vol. 13 sv. hukot ha-goyim.
 The Vilna Shas reads “Sadducees” but older versions have “Sectarians.” See Dikdukei Soferim, ad loc. n. 7.
 So Soncino, n. 6 translates according to Rashi.
 Rashi, ad loc.
 Rashba, Torat Ha-Bayit, 1:3 p. 17a. Cf. Rashbam, Ramban, Rabbeinu Bahya on Leviticus 19:26; Seforno on Leviticus 17:7; R’ Yonatan Eybeschutz, Pleiti, 12:1.
 Perhaps because there is a rational reason to slaughter into a pit, namely cleanliness. However, this raises the issue of whether a rational idolatrous practice may be followed. See further the responsa of R. David Tzvi Hoffman (below note 22), R. Marcus Horovitz (note 23) and R. Yechiel Ya’akov Weinberg (note 30) where this is discussed.
 41b sv. kol ikar
 Mishneh Torah, Hilkhot Shehitah 2:5
 ibid. 6
 Note that according to Rambam we only presume of being a sectarian someone who publicly slaughters directly into a pit. This is further evidence that Rambam’s view is that slaughtering into a pit was sectarian practice while slaughtering into a ditch that leads to a pit was only reminiscent of sectarian practice. Cf. Radbaz, ad loc.; Pri Hadash, Yoreh Deah 12:4.
 Cf. Tiferet Yisrael, ad loc. no. 31; Tosafot Rabbi Akiva Eiger, ad loc. no. 8. This seems to be a proof countering R. Daniel Sperber’s claim in The Edah Journal, 3:2 Elul 5763 p. 11 n. 26 that “the concern about appearing to emulate non-Orthodox movements does not arise as long as there are normative halakhic sources that may be relied on.” As we have seen, even something that was permissible in a different time, as reflected by normative halachic sources from that period, can be forbidden in a later situation. This is a prohibition that greatly depends on time and place.
 Cf. Nedarim 22a. It is certainly noteworthy that “the ways of peace” override this prohibition, implying that there must be a genuine halakhic need to set aside this consideration.
 R. Zalman Nehemiah Goldberg, “Tefillat Nashim Befarhesyah” in Tehumin, 5758 p. 122 cites Avnei Nezer, Hoshen Mishpat no. 149 that such encouragement of antinomians or heretics is biblically prohibited.
 Cf. Lawrence Schiffman, ibid. p. 54
 R. Samson Raphael Hirsch, Collected Writings, vol. 6 pp. 277-287
 Shulhan Arukh, Orah Hayim 150:5
 Responsa Hatam Sofer, vol. 1 no. 27
 Cf. Michael A. Meyer, Response to Modernity, pp. 57-61; Judith Bleich, “Rabbinic Responses to Non-observance in the Modern Era” in Jewish Tradition and the Non-traditional Jew, ed. Jacob Schacter, pp. 40-53.
 Melamed le-Ho’il, vol. 1 no. 16
 R. Marcus Horovitz, the only rabbi to dissent, agreed with R. Hoffman’s conclusion and his analysis of the prohibition against imitating sectarians. He only disagreed regarding the prohibition of following the ways of the Gentiles. See his entire letter to R. Hoffman in Responsa Mateh Levi, vol. 2 no. 6. This position of R. Horovitz’s regarding following the ways of the Gentiles was later quoted and disagreed with by R. Hayim Ozer Grodzenski in Ahiezer, vol. 4 (Jerusalem: 1992) no. 38.
 Orah Mishpat, Orah Hayim no. 36
 Da’at Kohen, Yoreh Deah no. 197
 Pesakim u-Ketavim, vol. 1 no. 14. Cf. ibid. no. 1.
 Seridei Esh, vol. 2 no. 80
 Ibid., vol. 3 no. 111. Cf. R. David Tzvi Hoffman, Melamed le-Ho’il, vol. 2 no. 109
 Seridei Esh, vol. 3 no. 93
 Hullin 41a sv uvashuk
 The omission of this entire issue of imitating sectarians from the responsa of R. Moshe Feinstein on this subject does not indicate disagreement over the prohibition. R. Moshe Feinstein gave brief responses to the question with little halakhic background. As R. Weinberg himself claimed, he and R. Feinstein wholly agreed and the only difference between them was that R. Weinberg discussed at length the underlying halakhic issues. See his letter to Ha-Pardes, Tammuz 5726 p. 37.)