Early Christianity, like Roman-era philosophical traditions, laid emphasis on everyday behavior, about how to live your life.

In the Marquette Lecture volume, I focus on the question in the title. I emphasize the social and political costs of being a Christian in the earliest centuries, and contend that many attempts to answer the question are banal. I don't attempt a full answer myself, but urge that scholars should take the question more seriously.

Early Christianity, like Roman-era philosophical traditions, laid emphasis on everyday behavior, about how to live your life.

Studies of the people named and described in earliest Christian texts show that, right from the earliest years, they included craftsmen, merchants, and owners of businesses. Of course, there were also slaves and poor among believers. By at least the second century, there were also believers from upper levels of Roman society.

I offer early Christianity as a case-study to show that the phenomena that we group under "religion(s)" comprise a somewhat artificial category, and that "religions" are not "all the same."

[Christians] practiced moderation and chastity in marriage, for example, and Galen was puzzled at how they were able to do so. His comments are a kind of back-handed compliment, I suppose.

Galen's observations reflect one of the distinctive features of early Christianity. Roman-era religion was mainly about ritual actions vis-à-vis the gods, and there was little to do with ordering behavior otherwise.