The apostle having closed the part of his epistle wherein he argues and proves various doctrines which are practically applied, here urges important duties from gospel principles. He entreated the Romans, as his brethren in Christ, by the mercies of God, to present their bodies as a living sacrifice to Him. This is a powerful appeal. We receive from the Lord every day the fruits of his mercy. Let us render ourselves; all we are, all we have, all we can do: and after all, what return is it for such very rich receivings? It is acceptable to God: a reasonable service, which we are able and ready to give a reason for, and which we understand. Conversion and sanctification are the renewing of the mind; a change, not of the substance, but of the qualities of the soul. The progress of sanctification, dying to sin more and more, and living to righteousness more and more, is the carrying on this renewing work, till it is perfected in glory. The great enemy to this renewal is, conformity to this world. Take heed of forming plans for happiness, as though it lay in the things of this world, which soon pass away. Do not fall in with the customs of those who walk in the lusts of the flesh, and mind earthly things. The work of the Holy Ghost first begins in the understanding, and is carried on to the will, affections, and conversation, till there is a change of the whole man into the likeness of God, in knowledge, righteousness, and true holiness. Thus, to be godly, is to give up ourselves to God.