Andreas of Caesarea : How can someone sin if he is not cut off from God in any way? — CATENA Augustine of Hippo : "Whosoever abideth in Him, sinneth not." In so far as he abideth in Him, in so far sinneth not. "Whosoever sinneth hath not seen Him, neither known Him." A great question this: "Whosoever sinneth hath not seen Him, neither known Him." No marvel. We have not seen Him, but are to see; have not known Him, but are to know: we believe on One we have not known. Or haply, by faith we have known, and by actual beholding have not yet known? But then in faith we have both seen and known. For if faith doth not yet see, why are we said to have been enlightened? There is an enlightening by faith, and an enlightening by sight. At present, while we are on pilgrimage, "we walk by faith, not by sight," or, actually beholding. Therefore also our righteousness is "by faith, not by sight." Our righteousness shall be perfect, when we shall see by actual beholding. Only, in the meanwhile, let us not leave that righteousness which is of faith, since "the just doth live by faith," as saith the apostle. "Whosoever abideth in Him, sinneth not." For, "whosoever sinneth, hath not seen Him, neither known Him." That man who sins, believes not: but if a man believes, so far as pertains to his faith, he sinneth not. — Ten Homilies on 1 John 4 Bede : Everyone who remains in Him does not sin. To the extent he remains in Him, to that extent he does not sin. — Commentary on the Catholic Epistles Bede : And everyone who sins has neither seen Him nor known Him. He speaks of the vision and knowledge of faith, with which the righteous even in this life delight in seeing God, until they reach the very form of His open vision in the future, of which it is said above: For we will see Him as He is. Therefore, everyone who sins has neither seen Him nor known Him. For if he had tasted and seen how sweet the Lord is (Psalms 34), he would by no means separate himself from the vision of His glory by sinning. And to the extent that the righteous recall the abundance of His sweetness and exult in His justice (Psalms 145), to that extent they strive to keep themselves from sins, seeking to harmonize with His immutable and incomparable justice. — Commentary on the Catholic Epistles Didymus the Blind : Just as the person who dwells in virtue and true doctrine does not sin and is not ignorant, so the one who remains in Christ, who is his righteousness and sanctification, does not sin. For how can someone act unrighteously when he is in the company of righteousness, and how can he be content to place corruption alongside holiness? Therefore anyone who sins is outside Christ and has no part or fellowship in him. — COMMENTARY ON 1 JOHN Hilary of Arles : Sinners have not seen Christ with the eye of faith, nor have they known him by putting that faith into practice in the right way. — INTRODUCTORY COMMENTARY ON 1 JOHN