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.

God certainly does not in either case effect or infuse blindness or hardness into the sinner (cf. James 1:13–14), yet neither does he only not take away blindness and hardness, by not circumcising the heart (Jer. 6:10, 26; Acts 7:51), or by not conferring spiritual light to the mind, or softness and malleability to the heart (Matt. 13:14–15; Isa. 6:9–10), but in addition: (1) on account of preceding sins, in a just and holy way, he takes away or diminishes the remnants of wisdom and moral goodness that a sinner has, and also augments and aggravates his original blindness and hardness.

God is said to blind and to harden men not only negatively (by not enlightening and softening) and privatively (by withdrawing his grace whatever it may have been after men have abused it) and permissively (by not hindering), but also positively. Not by bringing in blindness or hardness (which is natural to man), but both objectively by presenting external objects to them which although ordained to another direction by their own nature, yet he knows will be drawn in a different way by their vice; and judicially by smiting them internally with blindness (the light which they abused being taken away or extinguished); and by loosening the reins to their lusts and delivering them up and enslaving them to Satan.

For in those people God did not make the common sins but found them there, as we have noted before. And although God, in his just but to us hidden judgment, does abandon and harden them more and more (Romans 9:18), yet it is they who by their own free choice first become hardened (Romans 11:7) and abandon the benefits of general providence; they abuse God’s longsuffering, as Paul testifies in Romans 1:18, 26, and 28.

As for those wicked and ungodly men whom God, as a righteous judge, for former sins, doth blind and harden; from them He not only withholdeth his grace, whereby they might have been enlightened in their understandings, and wrought upon in their hearts; but sometimes also withdraweth the gifts which they had, and exposeth them to such objects as their corruption makes occasions of sin; and withal, gives them over to their own lusts, the temptations of the world, and the power of Satan.