It has been well said that if there is anything good in any man it is because it was put there by God. And something good — a new nature — has been imparted by God to every true believer in Christ.
While there is still within us “that which is begotten of the flesh,” there is also “that which is begotten of the Spirit,” and just as the one “cannot please God,” so the other always pleases Him.
Adam was originally created in the image and likeness of God, but he fell into sin and later “begat a son in his own likeness, after his image” (Gen. 5:3). It could not be otherwise. Fallen Adam could generate and beget only fallen, sinful offspring, whom even the law could not change. But “what the law could not do, in that it was weak [because of] the flesh, God, sending His own Son, in the likeness of sinful flesh, and for sin,” accomplished, “that the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit” (Rom. 8:3,4).
As Adam was made in the likeness of God, but fell, so Christ was made in the likeness of sinful flesh — though without sin — to redeem us from the fall, that by grace, through the operation of the Spirit, a new creation might be brought into being, “the new man which after God, is created in righteousness and true holiness” (Eph. 4:24).
Thus in addition to our fallen Adamic nature true believers, through faith, have also become “partakers of the divine nature” (II Pet. 1:4). This is the “inner man” of which Paul speaks in Eph. 3:16, and this “inner man” delights to do God’s will (Rom. 7:22).
The Adamic nature, which Scripture calls “the flesh,” is that which was generated by a fallen begetter. It is sinful in itself, even in the believer. It cannot be improved or changed. But “that which is born [or begotten] of God” always pleases Him. It was begotten by the Spirit of God Himself. This is why our Lord said to Nicodemus:
“That which is born of the flesh is flesh; that which is born of the Spirit is spirit….Ye must be born again” (John 3:6,7).