John Calvin Commentary Romans 6:13

"neither present your members unto sin [as] instruments of unrighteousness; but present yourselves unto God, as alive from the dead, and your members [as] instruments of righteousness unto God." — Romans 6:13 (ASV)

Nor present your members, etc. Once sin has obtained dominion in our soul, all our faculties are continually applied to its service. He therefore describes here the reign of sin by what follows it, so that he might more clearly show what we must do if we are to shake off its yoke.

But he borrows an analogy from military service when he calls our members weapons or arms (arma). It is as if he said, “Just as the soldier always has his arms ready to use whenever ordered by his general, and never uses them except at his command, so Christians ought to regard all their faculties as the weapons of spiritual warfare; if then they employ any of their members in the indulgence of depravity, they are in the service of sin.

But they have taken the soldier's oath to God and to Christ, and by this they are bound; therefore, they must be far from any association with the camps of sin.” — From this, those may also see by what right they proudly lay claim to the Christian name, who have all their members prepared, as though they were the prostitutes of Satan, to commit every kind of abomination.

On the other hand, he now commands us to present ourselves wholly to God. This requires us to restrain our minds and hearts from all wanderings into which the lusts of the flesh may draw us, so that we regard God’s will alone, being ready to receive His commands and prepared to execute His orders. Our members also must be devoted and consecrated to His will, so that all the faculties of both our souls and our bodies may aspire to nothing but His glory.

The reason for this is also added: that the Lord, having destroyed our former life, has not created us for another life in vain, which ought to be accompanied by suitable actions.