Galatians 4:8

Howbeit at that time, not knowing God, ye were in bondage to them that by nature are no gods.

This is a reference to the idolatry of the Galatians before they accepted Christ. "Bondage" is an apt term to describe the merciless, unfeeling subjection of the pre-Christian pagan world to the devices of idolatrous priests. True, the same word was used of Judaism, but there was a marked difference, due to the sensuality and immorality which were the stock in trade of the idol worshipers.

No gods ... Paul wrote the Corinthians that, "No idol is anything in the world, and there is no God but one" (1 Corinthians 8:4). See my Commentary on 1Corinthians under that verse.