Bible Commentary on Romans 6:18
"Being then made free from sin, you became the servants of righteousness" (Rom 6:18).
The Greek word that is translated as sin is hamartia. It is usually defined as “missing the mark.” Which gives one the picture of aiming an arrow at a target but missing it. This is not what it means.
Sin is not missing the mark, sin means to aim at the wrong object. One is not even aiming at the target. The target is pleasing God. Sin is not trying to please God but failing, sin is not even trying to please God. The aim of sin is pleasing self, not God. Sin is a wrong aim. Sin is selfishness.
Romans 3:9 says that "are all under sin." What does this mean? It means that as long as you are aiming to please self, you cannot please God. Selfishness bends all actions to the ultimate aim of one’s own life and interests. Sin makes you a slave of pleasing self. You are "under the power" of the selfish motive (Rom 3:9 NIV).
And Romans 6:22 explains, "But now being made free from sin [a wrong aim], and become servants to God [the right aim], you have your fruit to holiness, and the end everlasting life."
It is not wrong action that leads to separation from God, but the wrong aim of one’s life. Sin is living for oneself rather than God. "No man can serve two masters" (Matt 6:24). You will either serve self or you will serve God. As Romans 6:23 explains, "For the wages of sin [wrong aim] is death; but the gift of God is eternal life through Jesus Christ our Lord." Making Jesus Lord means making him master of your life.
The singular “sin” refers to the wrong aim, the dedication of the will to self-gratification. The plural “sins” refers to wrong acts, or selfish acts. These are acts that do not please or honor God. For a Christian, these wrong acts are out of harmony with one’s usual aim of pleasing God. As soon as the pressure of temptation is released, the aim of the will snaps back to pleasing God.
Let's bring this all together. Let me paraphrase our text, "After being freed from the wrong aim of selfishness, you became slaves to the right aim of benevolence." Benevolence is good willing, it is willing the highest good of God and humanity.