Whosoever is born of God doth not commit sin; for his seed remaineth in him: and he cannot sin, because he is born of God.
Whosoever is born of God - `everyone that is begotten of God.'
Doth not commit sin - his higher nature, as begotten of God, doth not sin. To be begotten of God, and to sin, are states mutually excluding each other. In so far as one sins, he makes it doubtful whether he be born of God. His seed - God's living Word, made by the Holy Spirit the seed in us of a new life: the continual mean of sanctification.
Remaineth - abideth in Him (note, 1 John 3:6; John 5:38). Not contradictory to 1 John 1:8-9: The regenerate show the utter incompatibility of sin with regeneration, by at once cleansing away every sin into which their old nature betrays them, in the blood of Christ.
Cannot sin, because he is born of God - `because it is of God that he is born' (cf. the Greek order with that of the same words in the beginning of the verse): not 'because he was born of God' х gegenneetai (G1080), perfect; present in meaning, not aorist]: not, Because a man was once for all born of God he never afterward can sin; but, Because he is born of God, the seed abiding now an Him, he cannot sin; so long as it energetically abides, sin can have no place. Compare Genesis 39:9, Joseph, "How CAN I do this great ... sin against God?" The principle within is at utter variance with sin, and gives a hatred for all sin, and an unceasing desire to resist it. 'The child of God receives wounds daily, and never throws away his arms, or makes peace with his deadly foe' (Luther). The exceptional sins of the regenerate are owing to the new life being suffered to lie dormant, and to the sword of the Spirit not being drawn instantly. Sin is ever active, but no longer reigns. The believer's normal direction is against sin; the law of God after the inward man is the ruling principle of his true self, though the old nature, not yet fully deadened, rebels. Contrast 1 John 5:18 with John 8:34: cf. Psalms 18:22-23; Psalms 32:2; Psalms 119:113; Psalms 119:176. The magnetic needle, the nature of which is always to point to the pole, is easily turned aside, but always re-seeks it.
Children of the devil - (note, 1 John 3:8; Acts 13:10.) There is no middle class between them and the children of God.
Doeth not righteousness. Contrast 1 John 2:29.
He that loveth not his brother (1 John 4:8) - a particular instance of love, which is the sum of all righteousness, and the token (not loud professions, and even seemingly good works) that distinguishes God's children from the devil's.