What is born of the flesh is flesh, and what is born of the Spirit is spirit

What is born of the flesh is flesh, and what is born of the Spirit is spirit. — John 3:6 NET

There is no promise made that we shall be set free in this life from the indwelling and the inworking of sin. Many think that they are to become progressively holier and holier, that sin after sin is to be removed gradually out of the heart, until at last they are almost made perfect in the flesh. But this is an idle dream, and one which, sooner or later in the case of God’s people, will be rudely and roughly broken to pieces. Nature will ever remain the same; and we shall ever find that the flesh will lust against the spirit. Our Adamic nature is corrupt to the very core. It cannot be mended, it cannot be sanctified, it is at the last what it was at the first, inherently evil, and as such will never cease to be corrupt until we put off mortality, and with it the body of sin and death. All we can hope for, long after, expect and pray for, is, that this evil nature may be subdued, kept down, mortified, crucified, and held in subjection under the power of grace; but as to any such change passing upon it or taking place in it as to make it holy, it is but a pharisaic delusion, which, promising a holiness in the flesh, leaves us still under the power of sin, while it opposes with deadly enmity that true sanctification of the new man of grace, which is wrought by a divine power, and is utterly distinct from any fancied holiness in the flesh, or any vain dream of its progressive sanctification.