Galatians 4: “Howbeit then when ye knew not God, ye did service unto them which by nature are no gods.”
To paraphrase: “How is it, then, that before you knew God you were enslaved by false gods? You were heathen when I came to you, enslaved by heathen customs, worshipping idols, misled by pagan priests. I introduced you to the Gospel of Jesus Christ, which sets you free from the bondage of sin and death–and now I hear that you are turning away from the light of grace and becoming enslaved again in rules and regulations that will keep you in bondage. Why? Why on earth would you do that?”
Why, indeed?