To be perfect as God is perfect, Christ already in us must progressively increase (He certainly needs no improvement!), and our already-crucified sinful nature must progressively decrease (it certainly cannot be improved). God would not have crucified His Son and us all with Him if we descendants of Adam could have been improved!
Just as Jesus became perfect by repeatedly driving the devil out of his human soul by speaking forth the word and living it (see Hebrews 5:8-9; Luke 4:1-13, also Part II), our sanctification progresses as we repeatedly drive the devil out of our souls by confessing these truths aloud and living them.
This is an excerpt from The Joint Enterprise of Grace and Faith: Making the Word Become Manifest – Part III. Since many others have started following The Lord Is With Us, He has put on my heart the need to emphasize this truth:
Using Paul’s terminology, Christians deal with two components: our new true self in Christ which is one with God in spirit in our hearts, and our old (already crucified!) self which rebels against God. The sanctification process is progressively increasing the amount of time during which we live through our new self united with Christ, and decreasing the amount time during which we live (a lie!) through our old self. We are changed by putting on the new self, what we already are in Christ, and by putting off that old self, the sinful nature – letting it waste away. (See 2 Cor. 4:16-18, 5:17; Gal 4:6, 5:16-18.)
So consider this: when we are irritated, which self is it feeling irritation: our new true self which is one with God in Christ, or the old fallen self which has already been crucified with Christ? Just Who do you suppose sent us that irritant?
It was Paul’s old self which called the person God had sent to help sanctify him a “thorn in my flesh, a messenger of Satan to torment me” (2 Cor. 12:7); Paul was likely making reference to King David’s comment, But evil men are all to be cast aside like thorns (2 Sam. 23:6). Note that what Paul’s old self thought was of the devil was actually from God to continue sanctifying Paul! The old sinful nature is a lie (it has been crucified already with Christ!), and is deceived. Praise God for the deliverance and life we have in Christ Jesus!
As written in the first post on this blog, overcoming in Christ is never overcoming the persons God sends our way that the old self finds offensive, but is overcoming through the indwelling Holy Spirit that old self so offended – all such persons are simply instruments in the hands of the sovereign Lord!
See also The Vital Distinction between “Becoming of Christ” and “Becoming Christ-Like“, Putting God’s Word into Practice – Applying Truth to the Lies, and The Least Appreciated Means of Grace: The Discipline of the Holy Spirit.