The Reformed: grace converts infallibly, yet conversion is a truly free work
The Reformed deny that the grace by which God turns men to himself is such that a man may sometimes block it and prevent its effect. They maintain that when God takes up the work of conversion it never happens that a man resists so as to stay unconverted, because divine grace is so powerful in the sinner that it brings about his conversion infallibly and irresistibly.
Yet they admit that this power does not stop man's conversion from being a truly free work, one that comes from the man not only actively but freely. The reason is that divine grace, however effective in itself, moves a man only in a way that suits and fits a rational and free creature.
It infallibly secures not just that the man acts and wills but that he acts and wills freely, so that in the good works to which grace moves him he acts from his own judgement, choice and deliberation no less than if he were acting without grace.
Latin
XLIII. Etsi vero negent Reformati gratiam per quam Deus homines ad se convertit, talem esse, ut homo quandoque obicem illi ponat, & effectum ejus impediat; & pertendant nunquam contingere, ut Deo conversionis opus aggredienti, homo sic resistat, ut inconversus maneat; quoniam gratiae divinae efficacia tanta est in homine peccatore, ut conversionem ejus operetur infallibiliter & insuperabiliter: fatentur tamen efficaciam illam non obstare, quominus hominis conversio sit opus vere liberum, & quod ab homine non solum active sed etiam libere procedit: quia, scilicet, gratia divina, quantumlibet per se efficax, hominem tamen non movet, nisi ut creaturae Rationali & liberae congruum & consentaneum est. Nempe praestat infallibiliter non solum ut homo faciat & velit, sed ut libere faciat & velit, & ut in operibus bonis, ad quae gratia illum movet, non minus agat ex proprio judicio, electione, & deliberatione, ac si sine gratia ageret.