The old empire early in it’s infancy did away with the worship of deities.
In the middle of it’s existence the old empire saw the birth of the Universities of Philosophy where Philosophies were studied, practiced, and shared with the citizens. At the height of the old empire the Universities of Philosophy were nearing the power of the arcane libraries and the legislature.
Each Philosophy represented a specific way to view the world and how to live in it as well as interact with others. There were dozens of different Philosophies, but after the Ruination many were lost.