Not long ago, everyone knew that Judaism came before Christianity. More recently, scholars have begun to recognize that the historical picture is quite a bit more complicated than that. In the Jewish world of the first century, many sects competed for the name of the true Israel and the true interpreter of the Torah—the Talmud itself speaks of seventy—and the form of Judaism that was to be the seedbed of what eventually became the Christian Church was but one of these many sects. Scholars have come to realize that we can and need to speak of a twin birth of Christianity and Judaism, not a genealogy in which one is parent to the other. In this book, the author develops a revised understanding of the interactions between nascent Christianity and nascent Judaism in late antiquity, interpreting the two "new" religions as intensely and complexly intertwined throughout this period. Although the "officials" of the eventual winners in both communities—the Rabbis in Judaism and the orthodox leaders in Christianity—sought to deny it, until the end of late antiquity many people remained both Christians and Jews. This resulted, among other things, in much shared religious innovation that affected the respective orthodoxies as well. Dying for God aims to establish this model as a realistic one through close and comparative readings of contemporary Christian texts and Talmudic narratives that thematize the connections and differences between Christians and Jews as these emerged around the issue of martyrdom. The author argues that, in the end, the developing discourse of martyrology involved the circulation and exchange of cultural and religious innovations between the two communities as they moved toward sharper self-definition.

The historical separation between Judaism and Christianity is often figured as a clearly defined break of a single entity into two separate religions. Following this model, there would have been one religion known as Judaism before the birth of Christ, which then took on a hybrid identity. Even before its subsequent division, certain beliefs and practices of this composite would have been identifiable as Christian or Jewish.In Border Lines , however, Daniel Boyarin makes a striking case for a very different way of thinking about the historical development that is the partition of Judaeo-Christianity. There were no characteristics or features that could be described as uniquely Jewish or Christian in late antiquity, Boyarin argues. Rather, Jesus-following Jews and Jews who did not follow Jesus lived on a cultural map in which beliefs, such as that in a second divine being, and practices, such as keeping kosher or maintaining the Sabbath, were widely and variably distributed. The ultimate distinctions between Judaism and Christianity were imposed from above by "border-makers," heresiologists anxious to construct a discrete identity for Christianity. By defining some beliefs and practices as Christian and others as Jewish or heretical, they moved ideas, behaviors, and people to one side or another of an artificial border--and, Boyarin significantly contends, invented the very notion of religion.