For much of its two thousand-year history, Christianity in the West has operated as if it were the only game in town, or at least the only game that mattered. While Christians were conscious of Jews as a minority in their midst and of Muslims at the borders of European Christendom, they engaged in surprisingly little dialogue with these two sister religions.¹ Christian theology—what Christians do whenever they think seriously about what they believe and what those beliefs mean for their own lives—tended to be a conversation in which Christians talked among themselves, as if the wider religious world did not exist, did not matter, or was simply a realm of the idolatrous and the damned.