Romans 6:19 - Wesley's Explanatory Notes

I speak after the manner of men — Thus it is necessary that the scripture should let itself down to the language of men. Because of the weakness of your flesh — Slowness of understanding flows from the weakness of the flesh, that is, of human nature. As ye have presented your members servants to uncleanness and iniquity unto iniquity, so now present your members servants of righteousness unto holiness — Iniquity (whereof uncleanness is an eminent part) is here opposed to righteousness; and unto iniquity is the opposite of unto holiness. Righteousness here is a conformity to the divine will; holiness, to the whole divine nature. Observe, they who are servants of righteousness go on to holiness; but they who are servants to iniquity get no farther. Righteousness is service, because we live according to the will of another; but liberty, because of our inclination to it, and delight in it.