"Let not sin therefore reign in your mortal body, that ye should obey it in the lusts thereof. Neither yield ye your members as instruments of unrighteousness unto sin: but yield yourselves unto God, as those that are alive from the dead, and your members
as instruments of righteousness unto God."
The two verses before us follow this vein of thought. Verse twelve is quite interesting. At first glance, it appears to be a command given directly to the believer; however, as the Greek text is examined, we find that it is a 3rd person command with sin as the object of the command. The same type of command was displayed when Jesus said, "He that hath ears to hear, let him hear." The truth is, it is God's desire that all who are willing hear and obey His truth. This is the same idea here in verse twelve. God, through His work of bringing about salvation, has given a general command to sin that it may no longer supremely rule in the body of a believer. Consider this illustration. A boy is being bullied by his older brother. The older boy is accustomed to doing this and yet the younger boy chooses to continue being around him even though he knows that he will be mistreated. Finally, tired of hearing the younger sibling's complaints of pain, the father of the two steps in and says, "John, stop bullying your younger brother and go sit in the corner." This is what God has done to sin's power over the believer. To view this verse as a command to an individual is not entirely incorrect, but this view is somewhat incomplete, because apart from God removing sin's power over me, I cannot hope to accomplish His command to forsake it.
Verse thirteen is then directed to us as believers. The commands in this verse are given in the 2nd person. After abolishing sin's death grip on us, God turns to us as individual believers and says, "Neither yield ye your members as instruments of unrighteousness unto sin: but yield yourselves unto God, as those that are alive from the dead, and your members as instruments of righteousness unto God." Consider the above illustration again. After disciplining the older brother, the father turns to the younger and says, "Now stay away from him. You know that he is going to beat up on you so don't play with him." The father has rescued the younger boy from the power of the elder one, but the younger has a responsibility to keep his distance from the older brother. Such is the case with us. We have been delivered from the power of sin, but each has a choice to live the old lifestyle or to live a new, holy, regenerated life before God through the power of Christ.