William Ames

He who uses as an instrument a man freely failing, to effect what is good, is not the author of the failure. … The wicked, while they sin, are not properly instruments of God moved, that is to say, without an internal principle of motion, but metaphorically, moved in such a way that they freely move themselves.

This very thing cannot be conceived, how something by way of an internal habit could be the cause of sin and not be sin. An internal cause inclining to act well is good.

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.

Whatever differs from the norm of the law is sin: but concupiscence in the regenerate differs from the norm of the law. Therefore.

It is illicit, not only to give consent to evil, but also to have an inclination, or propensity to such consent: because all our powers ought to be carried toward the good.