Mortification

The Apostle himself in Rom. 6 & 7 shows quite openly that concupiscence is sin properly so called: for not only does he often call it sin, but not good, evil, to be held in hatred, fighting against the law of God, to be crucified, mortified, and destroyed, and rendering that man miserable in whom it resides.

Moral corruption fighting against the law, for the crucifying and mortifying of which Christ himself died on the cross, if it be not properly sin, then Scripture has not explained to us what the property of any habitual sin is.

Every spark of fire is fire, and will burn; so is every thing of the law of sin, the last, the least of it, -- it is enmity, it will poison, it will burn. … Mortification abates of its force, but doth not change its nature. Grace changeth the nature of man, but nothing can change the nature of sin. Whatever effect be wrought upon it, there is no effect wrought in it, but that it is enmity still, sin still.

This corruption of nature, during this life, doth remain in those that are regenerated (1 John 1:8, 10; Rom. 7:14, 17–18, 23; James 3:2; Prov. 20:9; Eccl. 7:20); and although it be, through Christ, pardoned and mortified; yet both itself, and all the motions thereof, are truly and properly sin (Rom. 7:5, 7–8, 25; Gal. 5:17).

The corruption of nature, during this life, does remain in those that are regenerated (Rom. 7:18, 23; Eccl. 7:20; 1 John 1:8); and although it be through Christ pardoned and mortified, yet both itself, and the first motions thereof, are truly and properly sin (Rom. 7:23–25; Gal. 5:17).