How the Church Managed Before There Was Ethics
Stanley Hauerwas and Samuel Wells
It is important to remember that there was no NT when Christianity started. The difference between Jews and Christians was Jesus. That is why Christian was so foreign to pagans—they (Christians staked their claim to a strange philosopher (Jesus) and they worshipped him, a convicted criminal.
What Jesus taught cannot be separated from what he was.
The early church theologians are still important to understanding.
Augustine articulated the essential topics that are necessary to understand Christian life.
Thomas Aquinas built on Augustine, and was heavily influenced by Aristotle.
A book on the life of the saints by de Voragine was important for medieval Christians as a guide to how they should live. We, in modernity, would have a hard time with the miracles. In medieval times, the world view was much different and such things were expected.
While the Crusades and the Inquisition led to incredible excesses, they had their roots in good ideas. "It is not far from the discovery that everyone could be holy to the insistence that everyone should be."
The Reformation changed all of this. The unity, such as it was, was destroyed. Worship changed and some things became more private (reading the scriptures for example). The assumption that we can think our way out of challenges that face Christians in modernity led to the discipline of Christian ethics.