II Corinthians 4:16 and some other scriptures refer to 'the inner man'. What does 'the inner man' mean?
Let us look at all the verses concerning the "inner man" to help shed some light on your question.
"Therefore we do not lose heart, but though our outer man is decaying, yet our inner man is being renewed day by day. For momentary, light affliction is producing for us an eternal weight of glory far beyond all comparison, while we look not at the things which are seen, but at the things which are not seen; for the things which are seen are temporal, but the things which are not seen are eternal” (II Corinthians 4:16-18).
"I find then the principle that evil is present in me, the one who wants to do good. For I joyfully concur with the law of God in the inner man, but I see a different law in the members of my body, waging war against the law of my mind and making me a prisoner of the law of sin which is in my members" (Romans 7:21-23).
“That He would grant you, according to the riches of His glory, to be strengthened with power through His Spirit in the inner man, so that Christ may dwell in your hearts through faith; and that you, being rooted and grounded in love,” (Ephesians 3:16-17)
The outer man is our fleshly body. It decays and is temporary. It can be seen. The inner man is something that can be renewed daily, is eternal, and cannot be seen. The flesh is a husk for our spirit to reside in. It is not a permanent dwelling. "Then the dust will return to the earth as it was, and the spirit will return to God who gave it" (Ecclesiastes 12:7).
Paul is also contrasting the idea of spiritual exercise versus physical exercise, “Rather train yourself for godliness; for while bodily training is of some value, godliness is of value in every way, as it holds promise for the present life and also for the life to come" (I Timothy 4:7-8).
Being filled with the Spirit is another way to refer to the inner man being renewed and built up, “And do not get drunk with wine, for that is debauchery, but be filled with the Spirit, addressing one another in psalms and hymns and spiritual songs, singing and making melody to the Lord with your heart, giving thanks always and for everything to God the Father in the name of our Lord Jesus Christ, submitting to one another out of reverence for Christ" (Ephesians 5:18-21).
We must put off this flesh to be in eternity with God, “For we know that if the earthly tent which is our house is torn down, we have a building from God, a house not made with hands, eternal in the heavens. For indeed in this house we groan, longing to be clothed with our dwelling from heaven, in as much as we, having put it on, will not be found naked. For indeed while we are in this tent, we groan, being burdened, because we do not want to be unclothed but to be clothed, so that what is mortal will be swallowed up by life. Now He who prepared us for this very purpose is God, who gave to us the Spirit as a pledge. Therefore, being always of good courage, and knowing that while we are at home in the body we are absent from the Lord-- for we walk by faith, not by sight-- we are of good courage, I say, and prefer rather to be absent from the body and to be at home with the Lord" (II Corinthians 5:2-8).
by Alan Feaster