Perhaps the greatest purpose of Christianity is to take that which is only flesh and see it reborn as Spirit--to see spiritual life born where before there was only death. But then, even in the most mature of believers, there remain aspects of the old nature mixed in with--even at war with--the new. In frustration Paul cried, "I find then a law, that, when I would do good, evil is present with me" (Romans 7:21). But each Christian should, through the power of God, be winning that war.
Christ came to regenerate the spiritual side of man. "There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit. For the law of the Spirit of life in Christ Jesus hath made me free from the law of sin and death" (Romans 8:1-2).
Too many Christians still have their spirits buried deeply within the flesh, having "yielded [their] members servants to uncleanness and to iniquity" (Romans 6:19). But Christ came to change all that. "God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh: That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit" (Romans 8:3-4).
Through faith, "according to his abundant mercy [He] hath begotten us again" (1 Peter 1:3). To "beget" means to reproduce a like kind. Since He has "begotten us," we should be becoming like Him in attitudes and aims. "Let this mind be in you, which was also in Christ Jesus" (Philippians 2:5).
"And the very God of peace sanctify you wholly; and I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ. Faithful is he that calleth you, who also will do it" (1 Thessalonians 5:23-24). This is the object of Christianity. JDM http://www.icr.org/articles/type/6/