Saint Augustine: “He is his own destroyer who will not keep the commandments of the Physician.“

12th Tract on John 

The Physician cometh that, as often as in him lieth, he may heal the sick man. He is his own destroyer who will not keep the commandments of the Physician. Into the world came the Saviour. Why is He called the Saviour of the world, but because He came "into the world not to condemn the world, but that the world through Him might be saved"? If thou willest not be saved through Him, thou wilt be condemned of thyself. And why say I that thou wilt be condemned? Because it is written: "He that believeth in Him is not condemned." What then canst thou hope that He will say of "him that believeth not," but that He will be condemned And indeed He doth say farther: "He that believeth not is condemned already." He is condemned already, though the condemnation be not yet openly pronounced.

He is condemned already, for "the Lord knoweth them that are His." He knoweth them for whom is laid up the crown, and likewise them that are reserved unto the fire. His eye seeth in the field of the world the distinction of the wheat and of the straw, of the good corn and of the tares. "He that believeth not is condemned already." And why? "Because he hath not believed in the Name of the Only-begotten Son of God. And this is the condemnation that light is come into the world, and men loved darkness rather than light, because their deeds were evil." "Because their deeds were evil”, but, my brethren, is there one man of whom God findeth that his works are good? No, not one. God findeth all works to be (in themselves) bad. How then do we hear that some there be who do truth, and come to the light? For these words come anon: "But he that doeth truth, cometh to the light."

 Homily by St. Augustine, Bishop of Hippo