“But here arises a new question, how can it be that he who has once made such a progress should afterwards fall away? For God, it may be said, calls none effectually but the elect, and Paul testifies that they are really his sons who are led by his Spirit, (Romans 8:14) and he teaches us, that it is a sure pledge of adoption when Christ makes us partakers of his Spirit. The elect are also beyond the danger of finally falling away; for the Father who gave them to be preserved by Christ his Son is greater than all, and Christ promises to watch over them all so that none may perish. To all this I answer, That God indeed favors none but the elect alone with the Spirit of regeneration, and that by this they are distinguished from the reprobate; for they are renewed after his image and receive the earnest of the Spirit in hope of the future inheritance, and by the same Spirit the Gospel is sealed in their hearts. But I cannot admit that all this is any reason why he should not grant the reprobate also some taste of his grace, why he should not irradiate their minds with some sparks of his light, why he should not give them some perception of his goodness, and in some sort engrave his word on their hearts. Otherwise, where would be the temporal faith mentioned by Mark 4:17 ? There is therefore some knowledge even in the reprobate, which afterwards vanishes away, either because it did not strike roots sufficiently deep, or because it withers, being choked up. (98)
And by this bridle the Lord keeps us in fear and humility; and we certainly see how prone human nature is otherwise to security and foolish confidence. At the same time our solicitude ought to be such as not to disturb the peace of conscience. For the Lord strengthens faith in us, while he subdues our flesh: and hence he would have faith to remain and rest tranquilly as in a safe haven; but he exercises the flesh with various conflicts, that it may not grow wanton through idleness.” ..
In short, the Apostle warns us, that repentance is not at the will of man, but that it is given by God to those only who have not wholly fallen away from the faith. It is a warning very necessary to us, lest by often delaying until tomorrow, we should alienate ourselves more and more from God. The ungodly indeed deceive themselves by such sayings as this, — that it will be sufficient for them to repent of their wicked life at their last breath. But when they come to die, the dire torments of conscience which they suffer, prove to them that the conversion of man is not an ordinary work. As then the Lord promises pardon to none but to those who repent of their iniquity, it is no wonder that they perish who either through despair or contempt, rush on in their obstinacy into destruction. But when any one rises up again after falling, we may hence conclude that he had not been guilty of defection, however grievously he may have sinned.