What does Romans 6:20 mean?

Paul has posed only two possible realities for human beings. Initially, we are all slaves to sin, meaning we are under compulsion to obey our sinful desires. Those who express saving faith in Christ, on the other hand, are "slaves to righteousness," meaning we are so closely connected to Christ that it is becoming our nature to serve righteousness.

This leaves no room for a third option. Human beings cannot be morally independent or neutral. No moral choices exist other than serving sin or serving righteousness. This is consistent with the rest of Scripture, which depicts only two eternal categories of humanity: sinners who are saved by grace through faith alone (Ephesians 2:8; Revelation 22:1–5), and sinners who reject God and are separated from Him forever (John 12:48; Revelation 20:11–15).

Now Paul considers the advantages of either option. As in other parts of this book, he speaks from the perspective of a saved believer—his "we" means those who are Christians, not all men. Here Paul writes that when we were slaves of sin, before trusting in Christ and becoming Christians, we were free in regard to righteousness. Since we had no identity in Christ, we had no mandate or calling to do what was right. That was a "freedom," in a sense, Paul writes. He will show in the following verses that such autonomy comes at a high cost.