Romans 6:12-19 (New International Version)
12Therefore do not let sin reign in your mortal body so that you obey its evil desires. 13Do not offer the parts of your body to sin, as instruments of wickedness, but rather offer yourselves to God, as those who have been brought from death to life; and offer the parts of your body to him as instruments of righteousness. 14For sin shall not be your master, because you are not under law, but under grace.
15What then? Shall we sin because we are not under law but under grace? By no means! 16Don't you know that when you offer yourselves to someone to obey him as slaves, you are slaves to the one whom you obey—whether you are slaves to sin, which leads to death, or to obedience, which leads to righteousness? 17But thanks be to God that, though you used to be slaves to sin, you wholeheartedly obeyed the form of teaching to which you were entrusted. 18You have been set free from sin and have become slaves to righteousness.
19I put this in human terms because you are weak in your natural selves. Just as you used to offer the parts of your body in slavery to impurity and to ever-increasing wickedness, so now offer them in slavery to righteousness leading to holiness.