It should be readily apparent to most that Christianity no longer has the popular cultural sway it had even a generation ago. Moreover, the faith is not even united within itself, with dozens of larger denominations and thousands of independent churches, a variety of creeds, and even entirely different and incompatible understandings of faith, salvation, sin, and repentance.

Saint Vincent of Lérins, writing in the early 5^th century, in qualifying both what the core of Christianity is, and what it is not, gave his maxim: “Moreover, in the Catholic Church itself, all possible care must be taken, that we hold that faith which has been believed everywhere, always, by all.” What then was it that Christians of that time believed? What did Christianity look like in its first thousand years, and might an understanding of that early ethos inform increasingly embattled Christians today?