19 I speak in human terms because of the weakness of your flesh. For just as you presented your members as slaves of uncleanness, and of lawlessness leading to more lawlessness, so now present your members as slaves of righteousness for holiness.
In this verse Paul summed up the contrast between the dedication of the unbeliever and the believer. This is not a contrast between a true Christian and the non-Christian but between the non-Christian mode of life and the Christian mode of life.
19 I speak in human terms
Paul proceeded to give a human illustration of Christians who are under a new Master but were under Adamic slavery to personal gratification.
because of the weakness of your flesh.
Paul had to use a human illustration because the Roman church was warped in its capacity to understand biblical truth. Roman bias about a Roman citizen living in slavery prevented them from clarity of understanding regarding biblical truth.
For just as [comparison] you presented your members [human faculties]
The Holy Spirit picked up this phrase from previous statements in Romans 6 about that to which we yield our lives, speaking of presenting our human faculty as slaves to sin under the old epoch of living under Adam.
Now we come to another as/so comparison. Christians are to be as passionate in Christian living as they were living as non-Christians.
as slaves of uncleanness [impurity]
Non-Christians are characterized by submission to sin. “Uncleanness” is often used of sexual sins, but here it refers to any level of sinful corruption. It can include sins such as hatred, bitterness, resentment, or any sin that is out of phase with God.
and of lawlessness leading to more lawlessness [disregard of standards],
To be “lawlessness” is to disregard standards. Here the lawlessness is against God. The lawless behavior of non-Christians leads to more and ever-increasing rebellion against God. Lawlessness promotes more lawlessness. Roman Christians living previously as non-Christians threw themselves into personal gratification that more and more consumed their behavior.
so now present your members
This exhortation is similar to verse 13. The way to grow in Christ is to yield ourselves to God’s way of salvation by grace. God commands us to “present” our faculties to Him (imperative mood) because of His grace. This is a command only Christians can follow because they are in Christ. We can do this on account of what has already happened to us because of Christ. We are to act according to our status.
as slaves of righteousness
Christians should live their Christian lives according to the “righteousness” they already possess in Christ. The idea is this: “Live what is becoming to God and your new relationship to Him.”
for holiness [sanctification].
The literal meaning of “holiness” is set aside. Progressive sanctification is the movement of being set aside unto God. Christians are to “present” or set themselves before God as separated unto Him. This is a life set apart for God by accepting the grace of God.
Christians are to live their lives with a greater passion to yield themselves to God than the passion with which they yielded themselves to selfish gratification as non-Christians.
No Christian stands still in his walk with the Lord. Either he moves forward or backward. If a believer does not continue to apply principles of God’s Word to experience, he will go into reversionism in Christian living. He will develop a momentum of sinning. The longer he stays out of fellowship, the steeper the decline in his spiritual life.
It is important to progress in the Christian life with a life set apart unto God through Christ. If we do not have a clear sense that our life is God’s life, then we live for self-gratification.
1 Th 4: 3 For this is the will of God, your sanctification: that you should abstain from sexual immorality; 7 For God did not call us to uncleanness, but in holiness.