Romans 6:16-18 "Do you not know that when you present yourselves to someone as slaves for obedience, you are slaves of the one whom you obey, either of sin resulting in death, or of obedience resulting in righteousness? But thanks be to God that though you were slaves of sin, you became obedient from the heart to that form of teaching to which you were committed, and having been freed from sin, you became slaves of righteousness."

The Bible teaches that we are slaves, we are creatures that serve a master, and we can tell who our master is by who we obey.  Now we can be enslaved to sin (which is our natural condition) and obey the lusts of our flesh which can be unique for each and every person.  The result of being sin's slave is death (see also Romans 6:23).

But we can thank God that when we were enslaved to sin, we were freed by Christ and instead have become slaves of righteousness.  We now serve a new master, one that pleases God.

Whom do you serve?