The history of the Jewish community in Amsterdam in the 17th century is the amazing story of a great reclamation project to save Jews and Judaism. The descendants of Jews forced to convert to Catholicism in 1497—known as “conversos”—found a home to return to Judaism in the Dutch city. This return to Judaism was often 100 years after the initial conversion to Christianity of their ancestors. In Portugal they lived outwardly as Catholics. To do otherwise would invite the wrath of the Inquisition. These conversos had no access to rabbis, Jewish teachers or Jewish texts.Yet, even a century after the initial conversion to Christianity, the descendants of the original conversos were returning to Judaism. The theology of the “marranos” —those conversos who held on to their Jewish identity—is complex. Marranos, influenced by the Catholic society in which they lived, often referred to the heroes of the Bible as “saints.” Fasting was also common among Marranos because it was both a vehicle for repentance and a covert way to express their Jewish faith that could go undetected by their neighbors or the Inquisition. Because living openly as Jews was forbidden, the crypto-Jews of Portugal expressed their Jewish identity as a rejection of Catholicism. This included a rejection of worship of images. It is hard to imagine today the courage that it took for adult males to undergo circumcision in an age before anesthesia. It is obvious that being Jewish was so important to them that they were willing to endure the pain. Once we realize the great reclamation project of early modern Amsterdam, we can begin to understand the severity of the excommunication of Benedict Spinoza from the community. The “herem” or ban was usually not as severe as that placed on the philosopher. But Spinoza’s ideas—that the Bible was not divine, that there were no miracles, that there was no God of history but a God of natural law—were very dangerous in an atmosphere that was devoted to bringing the descendants of converted Jews back to Judaism. The communal leaders in Amsterdam had to throw Spinoza out—his ideas undermined everything for which the community stood. There was nothing in the background of Spinoza’s family that would indicate antinomianism and heresy. But there is no doubt that having lived so long without Jewish law and Jewish teachers weakened trust in rabbinic authority and created a strong ambiguity in the attitude toward Jewish tradition. Nevertheless, Spinoza was an exception. The Jewish community of Amsterdam was actually a great success in its mission. Conversos who made the journey to the Netherlands had communal and educational institutions that reintegrated these descendants of converts back into Jewish tradition and the Jewish community. Amsterdam should remain a model for Jewish communal and educational institutions today in reaching out and bringing back Jews who are unaffiliated with any synagogue or Jewish organization. It is a worthy mission and a noble goal that should be pursued.