Objection 71: Paul says, “For which cause we faint not; but though our outward man perish, yet the inward man is renewed day by day.” 2 Cor. 4:16. This proves that the real man, the soul, is something different from the body, and flourishes despite the perishing of the body.
Believers in the immortal-soul doctrine seem to feel that if a Bible writer speaks of a contrast between one aspect of a person and another, between the body and the spirit or the soul, that proves the truth of their doctrine. But we also believe there is a difference between body and spirit, or between body and soul. We are to glorify God in our body and in our spirit, the Scriptures declare. We simply insist that the Scriptures nowhere say that the soul, or spirit, is a distinct, a separate, immortal entity encased within a shell, the body.
Paul wrote to the Corinthian church about his being “absent in body but present in spirit.” 1 Cor. 5:3. Did Paul wish us to understand that he left his body in one place while his disembodied consciousness flitted off to Corinth? Then why seek to discover an immortal-soul doctrine in his words: “Though our outward man perish, yet the inward man is renewed day by day”? Let’s not make this more difficult than it is. The “inner man” is another way of describing the spiritual aspect of a person. The “outer man,” by contrast, would be the visible, external aspect of a person.
In several passages Paul speaks, in variant language, of this “inward man.” To the Ephesians he wrote, “That He would grant you, according to the riches of his glory, to be strengthened with might by his Spirit in the inner man; that Christ may dwell in your hearts by faith.” Eph. 3:16-17. Again he writes, “You have put off the old man with his deeds; and have put on the new man, which is renewed in knowledge after the image of him that created him.” Col. 3:9-10. In these passages and others, Paul is discussing the spiritual regeneration that comes with conversion. The phrase "inward man" or "inner man" or "new man” all refer to the change that comes to us when Christ enters our hearts, and our old sinful habits and customs are cast off.
As Paul declares, “I am crucified with Christ: nevertheless I live; yet not I, but Christ lives in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me.” Gal. 2:20. The "inward man" is renewed daily by the presence of the indwelling Christ who causes us to grow constantly in spiritual stature even though the body is inevitably declining as we grow old.