"Religions" of the Roman world varied. Most of it was ritual practices. There were periodic occasions when cities honored their guardian deities with sacrifices and ceremonies, to ensure that they stayed happy and kept the city safe.

Justin Martyr says that he was impressed in his study of the Old Testament, at the seriousness and contents of these writings, and became convinced that Jesus fulfilled these texts.

I think Rodney Stark makes a substantial contribution to the study of early Christianity in posing the kinds of questions that he pursues (which reflect his social-science background).

[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.

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

Some modern scholars contend that in terms of what "religion" was in that [Roman-era setting], you can't even call Christianity a religion.

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."