There is a tendency to argue in favor of Roman Catholic practices,

[zipplewrath]

12. The Catholic Church WAS the civil authority

For many reasons far too many to list, the Catholic Church WAS the civil authority in much of Europe during much of that time. They "owned" much of the land. They provided a central authority for the resolution of disputes. And they provided the context for various rituals from birth through death.

To the OP's point, we incorporate and accept some remnants of Catholic teaching, not because of "god" but because virtually our entire culture emanates from the Catholic Church such that it is in many ways the underpinnings of our culture. Of course, the Roman Catholic Church formed much of its structure from the governmental structures that proceeded it, so much of it is not a creation of the church, even more so separating it from any concept of "god", at least the christian god.