When his light is taken away, nothing remains but blindness and darkness: when his Spirit is taken away, our hearts become hard as stones: when his guidance is withdrawn, we immediately turn from the right path: and hence he is properly said to incline, harden, and blind those whom he deprives of the faculty of seeing, obeying, and rightly executing.

God may be said to cause men to err from his ways, and to harden their hearts from his fear, by withholding, upon their provocation, some such supply of his Spirit and actings of his grace as they have formerly enjoyed, to keep up their hearts to the ways and in the fear of God.

Thus God is said to harden men, not by positive hardening, or working anything in the creature, but by not working, not softening, leaving a man to the hardness of his own heart, whereby it is unavoidable, by the depravation of man’s nature, and the fury of his passions, but that he should be further hardened. … If you put fire near to wax or resin, both will melt; but when the fire is removed, they return to their natural quality of hardness and brittleness. The positive act of the fire is to melt and soften, and the softness of the rosin is to be ascribed to that, but the hardness is from the resin itself, wherein the fire hath no influence, but only a negative act by a removal of it; so when God hardens a man, he only leaves him to that stony heart which he derived from Adam, and brought with him into the world.

Thus, God is said to harden a wicked man because of his demerits when, being provoked by that man’s impiety, He takes occasion to withdraw granted grace and to do certain things through which He knows that this man will grow worse.

When God is here spoken of as hardening some of the children of men, it is not to be understood that God by any positive efficiency hardens any man's heart. There is no positive act in God, as though he put forth any power to harden the heart. To suppose any such thing would be to make God the immediate author of sin. God is said to harden men in two ways: by withholding the powerful influences of his Spirit, without which their hearts will remain hardened, and grow harder and harder; in this sense he hardens them, as he leaves them to hardness. And again, by ordering those things in his providence which, through the abuse of their corruption, become the occasion of their hardening.