Early Orthodox (or proto-Orthodox) Christians writing after the apostolic period but before western Christendom’s adoption of the Nicene Creed (325 CE) are sometimes called the Ante-Nicene Fathers, and there is a fascinating (and rather thick) book I’m reading that catalogues quotes from them concerning 700 different subjects: A Dictionary of Early Christian Beliefs (Ed. David Bercot, 1998).
The book is quite a revelation, for it is striking how different the Ante-Nicene Fathers’ Christianity is from 21st century Christianity (especially as broadly practiced by American Protestants). The overwhelming impression one gets from reading these early Christians’ writings is that their sensibilities were more in line with contemporary Pakistani Muslim fundamentalists than American Protestant fundamentalists (women in these early Christian communities were veiled—their figures hidden—and worldly theater and entertainments were strictly avoided. Men, in keeping with some passages in Leviticus—19:27 and 21:5—did not shave. Even clothes containing dyes were frowned upon).
In fact, I seriously doubt that any of the early Orthodox Christian writers would regard contemporary American Christians as Christians at all. Here, for example, is Justin Martyr (c. 160 CE, dictionary pg. 128):
Let it be understood that those who are not found living as He taught are not Christians—even though they profess with the lips the teachings of Christ.
And what did these early Christians believe that Jesus taught? A determined turning away from earthly pleasures, and toward material simplicity. Here’s Lactantius (c. 304-313 CE, pg. 132):
True things must be preferred to false; eternal things, to those that are temporary; useful things, to those that are pleasant. Let nothing be pleasing to the sight but that which you see to be done with piety and justice. Let nothing be agreeable to the hearing but that which nourishes the soul and makes you a better man.
In other words, these early Christians were serious—very serious—fundamentalists. Psychologically, they deeply embedded and isolated themselves in a very strict—and determined to avoid sin and doubt—subculture. Here’s Ignatius on hearing any ideas about Jesus contrary to what he believed the apostles taught (c. 105, pg. 181):
[S]top your ears when anyone speaks to you contrary to Jesus Christ, who was descended from David, and was also of Mary; who was truly born and did eat and drink.
Anyway, the book is quite an eye-opener concerning the origins of Christian fundamentalism—and the rationales functioning in its first practitioners—and can be found at Amazon here.