Augustine of Hippo

Again they say, "Who made the devil?" He made himself; for the devil was made by sinning, not by nature. "Or," they say, "God should not have made him if he knew that he would sin." On the contrary, why should he not have made him? For through his own justice and providence God corrects many as a result of the malice of the devil. Or have you perhaps not heard the apostle Paul saying, "And I handed them over to Satan so that they might learn not to blaspheme"?