Romans 6:12

‘Do not therefore let sin reign in your mortal body, that you should obey its strong desires,'

In consequence of the fact that we are dead to sin through our association with Christ's death we are not to let sin reign in our mortal bodies, in other words in ourselves. Sin has been ejected from its throne. It no longer has a right to reign in a Christian. Now grace reigns through Christ's gift of righteousness (compare Romans 5:21). Sin, along with its strong desires, must therefore now be repudiated. It must not be obeyed. For we have died to it. It no longer has any rights in our lives.

Paul recognises that there are within himself, and within all men, ‘strong desires' (compare Romans 7:14). And these were what led men into sin. But they are to be repudiated. In so far as they are desires to sin they have been crucified with Christ, and by becoming Christians we have denied their right to control over us. Thus by the Spirit we are to overcome them and refuse them any part in our lives. We are to put ourselves under the control of the Spirit. This is an essential part of our spiritual battle (Galatians 5:16 onwards).

‘In your mortal body.' There is in this a reminder that as we now are our bodies are subject to death, this in contrast with being ‘alive from the dead' (Romans 6:13). Thus to succumb to sin is to encourage death. But we are not to see the body here as distinguished from what we call ‘the soul'. It represents the whole person. Sin must not reign in us.