Listen to what St. Augustine has to say: "Look at the way," he tells us, "in which the Devil behaves towards the sinner. He acts like a jailer who has a great many prisoners locked up in his prison but who, because he has the key in his pocket, is quite happy to leave them, secure in the knowledge that they cannot get out. This is his way of dealing with the sinner who does not consider the possibility of leaving his sin behind. He does not go to the trouble of tempting him. He looks upon this as time wasted because not only is the sinner not thinking of leaving him, but the Devil does not desire to multiply his chains. It would be pointless, therefore, to tempt him. He allows him to live in peace, if, indeed, it is possible to live in peace when one is in sin. He hides his state from the sinner as much as is possible until death, when he then tries to paint a picture of his life so terrifying as to plunge him into despair. But with anyone who has made up his mind to change his life, to give himself up to God, that is another thing altogether."
(from the Book “The Sermons of The Cure of Ars”, TAN Books 2013, Page 126-127)