Romans 6:19

I speak after the manner of men because of the infirmity of your flesh: for as ye presented your members as servants to uncleanness and to iniquity unto iniquity, even so now present your members as servants to righteousness unto sanctification. [But thanks be to God that these principles are not mere matters of speculation with you, but have been tested and applied by you in your actual experience, for whereas ye were once the slaves of sin, ye, of your own free will and heart's choice, changed your masters, and became, by your obedience to it, the servants or slaves of the principles set down in the Christian or gospel form of teaching whereunto (as is the custom when slaves are sold) ye were delivered for service. Now, I use this illustration of the transfer of slaves, which is taken from daily, secular affairs, not because it is a perfect and adequate representation of your change of relationship in passing from the world unto Christ, but because your fleshly nature clouds your understanding of spiritual ideas, and you therefore comprehend them better if clothed in an earthly or parabolic dress, even if the figure or illustration is defective. Christ is far from being a tyrannical master, and certainly cherishes no such feelings towards you as those which a slave-owner holds towards his slaves; yet the figure nevertheless aids you to comprehend the point which I am now discussing, for you can readily see that, as under the old slavery, you presented your members as servants to impurity and to lawlessness for the purpose of being lawless, so, under the new service, it behooves you to now present your members as servants to righteousness for the purpose of becoming sanctified, or holy.]