Communities have boundaries. Only in our time of epistemic chaos could this self-evident truth be put in doubt.Inherent to the idea of a community is that there is an inside and an outside. That doesn’t mean community is a self-sufficient or isolated system, but a limit to belonging does exist. That limit—think about the body's skin—not only separates the inside from the outside but also makes exchanges between these two dimensions possible.The Jewish world is facing a sometimes acrid debate about “the boundaries of community” that expresses itself mostly around the issue of Zionism and whether being an anti-Zionist puts one “beyond the pale.”Granted, the debate is mostly theoretical because in most countries the Jewish community has no coercive power over its members, and even in Israel, being an anti-Zionist will not cause you to lose civil or citizenship rights. But it’s nevertheless an important debate, and recent articles in the pages of this magazine have argued both sides. Gil Troy and Natan Sharansky claim that those who oppose Zionism and work or advocate against the very existence of Israel as a Jewish state are “un-Jews” because they are actively trying to dismantle an essential component of most Jews’ Jewishness. In response, Shaul Magid argues that calling anti-Zionists “un-Jewish” is an absurdity because, according to him, in many cases anti-Zionism is based on Jewish sources and is even more “loyal” to the sources than Zionism itself, which came from a revolution against traditional Judaism (and was a minority movement until shortly before the establishment of the State of Israel). These positions are emblematic of two camps within the Jewish community. While some believe Zionism to be inseparable from 21st-century Judaism, others believe in decoupling Judaism from Zionism and that being an anti-Zionist should not exclude anybody from the “Jewish establishment” (to the extent that such a thing exists). In many cases, this evolves into a broader argument against the very setting of boundaries and any attempt to enforce them.It is true that some of the vitriol against anti-Zionists is excessive and even dangerous; it may even be strategically unwise, as it tends to radicalize those people even more. Yet the non-exclusionary position ignores something central: Judaism, like any other culture, has normative positions that set the limits of belonging. But throughout Jewish history, new ideological positions became normative, and others were weeded out or excluded. The fact that an ideology was rooted in Jewish sources didn’t guarantee automatic acceptance.Jewish history presents many instances of boundaries being set, sometimes resulting in schisms. Those processes of “separation” weren’t always simple, fast, or straightforward, but they have been a constant feature of the Jewish journey. Christianity is one such example. It was started by Jews, was deeply rooted in Jewish texts, and was purported to present a more “authentic” view of Judaism with what it believed to be the “correct” interpretation of biblical prophecies. That schism represented a dialectical process toward separation led by both Jews and early Christians. The breaking point was probably the defeat of the Jamesian faction (named after Jesus’ brother who believed that Christians—then called Nazarenes—were an integral part of the Jewish people and subject to Jewish Law) by the Paulist faction, a group that looked to convert Gentiles and replace the obligations of Jewish Law with belief in Jesus. Originally, Jewish authorities were split, some favoring the exclusion of the Nazarenes, while others considered them to be simply another of the era's many sects. Eventually, the rabbinic authorities of the time understood that Christianity, with its belief in Jesus as a resurrected messiah, put them “beyond the pale”; the Paulist rejection of Jewish Law was the last straw in that separation process. A key factor was, simply, that the overwhelming majority of Jews had rejected Jesus’ divinity. Rabbis were not only defending orthodoxy but channeling the majority sentiment as well.Eight centuries later, the Karaites, of the Karaite movement led by Anan ben David, presented similar but different dilemmas. The Karaites believed that only the “written Torah”—not its rabbinical interpretations, called collectively “oral Torah”—should be the basis for Jewish observance. Karaist-adjacent attitudes had been present in Judaism since the time of the Second Temple (Abraham Geiger, for example, proposes that Karaites continue some Sadducean traditions). But in the 10th century the movement enjoyed a golden age of sorts that demanded a definition in terms regarding its role in Judaism. Rabbinical opinions diverge, as they often do, about how deviant Karaism was; but a consensus developed around the notion that Karaim were not, as a community, part of the Jewish people. Most medieval Jewish sages, notably Rabbi Yehuda Halevi, wrote powerful justifications for that exclusion. It wasn’t so straightforward, however, for individual Karaim. Maimonides, for example, says that a Karaite can’t be held personally responsible for the beliefs that his parents instilled in him and should be allowed back into the Jewish community if that's what he wants. Today the Israeli chief rabbinate considers some Karaim to be Jews, even though they are not considered, as a group, to be part of the Jewish people. Here again, it was critical that the majority of the Jews of the time rejected Karaism.In other cases, like the followers of the false messiah Sabbatai Zevi, a herem (excommunication) was applied, signifying that he and his believers were not considered part of the community. The setting of boundaries wasn’t easy in this case either. Many prominent Jews believed in Zvi’s messianism; entire communities celebrated his arrival and some in Hamburg and Amsterdam sold their property and moved to the Holy Land in anticipation of redemption. The popularity of the movement was such that Rabbi Abraham Sasportas, a leading advocate of the herem, was harassed and ridiculed. But the majority opinion shifted dramatically when two major lines were crossed: Zvi’s declaration that many mitzvoth did not need to be fulfilled anymore and, of course, his final conversion to Islam in 1666.Not every polemic in Jewish history resulted in a schism or exclusion. The emergence of Kabbalah after the 12th century and Hasidism in the 18th century, for example, were both close calls. The “orthodoxy” of the time was extremely nervous about kabbalistic descriptions of the "inner life of God,” which to them appeared dangerously close to polytheism. Hassidism posed many dilemmas; the most serious was likely the role attributed to the “rebbe” as a sort of intermediary between man and God. These fights were, in fact, more vicious that those we see today between Zionists and anti-Zionists, including some episodes we'd all prefer to forget, such as denunciation to the czarist authorities, imprisonment, and the like. The leading rabbi of the time, the Vilna Gaon, led the Misnagdim (opponents) and issued a ban against the Hasidism. Over time, however, a consensus seemed to emerge; as long as these new movements did not reject the monotheistic idea and continued fulfilling mitzvoth in a traditional fashion, they were considered “within the pale,” even though the divisions between Hasidim and Misnagdim continue to this day.In the 1970s, Jews for Jesus, the most visible face of the Jewish messianic movement, presented yet another dilemma, for they claimed to be fully Jewish while recognizing the divinity and messianic nature of Jesus as the Son of God. Consensus in this case was easier to reach. Not only rabbinical authorities but ordinary Jews tend to think the frontier of Judaism stops at belief in Jesus. In fact, in a rare moment of unity, all Jewish denominations signed on to a declaration that said that “though Hebrew Christianity claims to be a form of Judaism, it is not…”Zionism is indeed a “new” movement. It is of course deeply rooted in Jewish history and belief, but it is clearly a product of the historical realities of the 19th century, in which groups of humans bound by certain particularities started to see themselves as “nations” and “peoples” with the right to sovereignty and self-determination within the framework of a nation-state. Some activists cite this supposed novelty as an argument against making Zionism a key parameter of belonging to the Jewish collective. How, they ask, can a movement that is so new become the litmus test of belonging to an ancient people?But the idea that a new movement can gain acceptance and become normative to the exclusion of others is at the root of Judaism as we practice it today. Rabbinic Judaism triumphed over the Temple-worshipping priestly caste and redefined the basic tenets of Judaism. A new movement, in this case the Pharisees, changed the normative positions of Judaism over the course of a century, then excluded from the community those who didn’t share them. Pharisaic Judaism was as “new” in the first century BCE as Zionism is today. It was as influenced by external forces (like Greek philosophy and hermeneutics) as Zionism was influenced by Hegelian views and Italian national “Risorgimento.” Yet, despite their novelty, key beliefs of the Pharisees, such as the “world to come” or resurrection of the dead, became a sort of litmus test in order to be accepted within the rabbinical community. In a way, as Zionism does today, Pharisaic Judaism introduces groundbreaking innovations and then shifts the boundaries by redefining belonging. Here too, a key factor was that a vast majority of the Jewish people, especially after the destruction of the Temple, embraced Pharisaic Judaism. In that sense, Zionism is deeply inscribed in a Jewish historic dynamic of boundary setting. If one argues against Zionism redefining the limits of belonging, one should also reject the lines drawn by Pharisees and welcome back into the fold the people they excluded—Saducees, Karaites, and Christians—as full members of the Jewish people.A series of major events in the world and in Jewish history led to the emergence of modern Zionism and the resurrection of Jewish statehood in the land of Israel. Those events also brought the overwhelming majority of Jews to consider Zionism as a key element in 21st-century Judaism—so central that denying it puts one beyond the pale. There’s nothing new or intrinsically wrong in that state of affairs. In the same way that Pharisaic Judaism took a good century (and the massive dislocation caused by the destruction of the Temple) to become normative, so Zionism took a hundred years, the massive trauma of the Shoah, and the creation of the State of Israel to become mainstream and normative.Once a position becomes normative, it’s only natural that communal structures will try to find ways to enforce them. One may speak pejoratively about Judaism's “enforcers,” but isn’t enforcement a necessary if fraught exercise for communities that seek to retain a minimum of cohesion?While the existence of ideological limits is a necessity for the existence of a community, we can argue about how those limits are set and by whom. Certainly, claiming that some beliefs don’t belong with us doesn’t mean establishing an inquisition.There are, of course, many practical issues with the setting of communal boundaries and normative positions. How does such a process even work? What are the consequences for those no longer considered within the pale? How is any of this even relevant for a community that continues to exist largely in diaspora and thus with no centralized source of coercive power? Excommunication might have had dire consequences in the 16th century, but today, most Jews would shrug or even mock a herem.Moreover, Judaism has traditionally policed practices more than faith. “The one who profanes the Sabbath in public” was excluded from the community, but not the one who held controversial beliefs. The earlier examples of Kabbalah and Hasidism are cases in point. Shouldn’t we differentiate, then, between anti-Zionist beliefs and anti-Zionist “practices”? (The difference, for example, between the Hasidic Satmar community, which maintains a mostly ideological anti-Zionism, and Neturei Karta, which actively campaigns against the Jewish state.) And should the limits we set affect the individual or only ideas, as in the case of the Karaim? Halachically, a Jew remains a Jew even if she sins, so can we actually “exclude” people at all? Last but not least, “Zionism” is not one ideology but many, and if Zionism is to be a key parameter of belonging, we need to define what the term actually means.All these issues are real and complicated, so much so that they may make this debate a mere thought experiment. But I believe our community needs a conversation about limits, boundaries, and normative positions. We need it because in our century, belonging has become fluid and uneasy. There’s a deep malaise around defining collective entities, like peoples, countries, and communities. The paradigm of “without borders,” cherished by many, won’t help us.True, the attempt to set boundaries is sometimes clumsy, intolerant, and ignorant. Bad actors appoint themselves as ultimate judges of right and wrong. But two wrongs don’t make a right: The fact that limits are not always set in the right way doesn’t mean that limits shouldn’t exist. The fact that the wrong people act as “enforcers” doesn’t mean that “enforcement” is, in itself, negative. The setting of boundaries should be organic, informed, responsible, and respectful. It should, above all, represent the views and ideas of the majority of Jews. The acrimony of the communal debate around Israel and the general polarization of society make these conversations incredibly difficult, but paradoxically, more necessary. Historically, “anything goes” has never been the Jewish answer. The truth is, Zionism has become key to the Judaism of a very large number of Jews. On the one hand, close to 50 percent of the world’s Jews live in Israel itself, and the Zionist enterprise is inextricably linked to their lives. Denying Zionism implies disregarding and denying a critical piece of their lived experiences. On the other hand, most diaspora Jews (surveys place the percentage in the high 80s) recognize the connection with Israel as a central part of their Jewish identities. Supporting the Zionist enterprise has become normative for most and a matter of life and death for millions. In that context, claiming that support for anti-Zionism puts one, in some important way, outside of the Jewish people is less a point of debate than a literal description of reality. The difficulties that any boundary-setting exercise entails shouldn’t make us lose sight of this obvious fact.This may be another one of those historical moments that call for a redefinition of the boundaries of belonging. Because this is an important conversation, we need to wrestle it away from the extremists and the merchants of hate. We need to educate the community to have these conversations intelligently and respectfully, grounded in the sources and historical experiences of Judaism. We need a broad community dialogue that is as empathetic as it is learned. Ultimately, limits are going to be drawn. They always are; but how that happens is largely our choice.