Augustine of Hippo : The enemy does not understand the power of the Lord's sacrament, which is available in saving baptism for those who believe and hope in him. He still thinks that sins can prevail even over the baptized, because they are being tempted by the frailty of the flesh. He doesn't know where and when and how the complete renewal of the whole person is to be perfected, which is begun and prefigured in baptism and is already grasped by the most assured hope. — SERMON 363.2