Albert Barnes Commentary Romans 6:12

"Let not sin therefore reign in your mortal body, that ye should obey the lusts thereof:" — Romans 6:12 (ASV)

Let not sin therefore. This is a conclusion drawn from the previous train of reasoning. The result of all these considerations is that sin should not be allowed to reign in us.

Reign. To have dominion; to obtain ascendancy, or to rule.

In your mortal body. This means in you. The apostle uses the word "mortal" here, perhaps, for these reasons:

1. To remind them of the tendency of the flesh to sin and corruption, as equivalent to "fleshly," since the flesh is often used to denote evil passions and desires (Compare to Romans 7:5, 23; 8:3, 6), and

2. To remind them of their weakness, as the body was mortal, was soon to decay, and was therefore liable to be overcome by temptation. Perhaps, also, he had his eye on the folly of allowing the "mortal body" to overcome the immortal mind and to bring it into subjection to sin and corruption.

That you should obey it. This means that sin should gain such ascendancy as to rule entirely over you and make you its slave.

In the lusts of it. This means in its desires, or propensities.