To commit sin is a breach of God's law, a frustration of God's work of redemption, and the manifestation of a principle which betrays kinship with the devil. A man begotten of God will be in moral affinity with God, for which reason righteousness and brotherly love will characterise him.
1 John 3:4. sin is lawlessness: i.e. not the absence of law, but opposition to it. Law does not cease to exist for the Christian, and all opposition to it, so far from being morally unimportant, is rebellion.
1 John 3:5. he was manifested: i.e. at His Incarnation. Righteous Himself, the work of Christ is to make us righteous too (cf. 1 John 3:8).
1 John 3:6. sinneth not: i.e. habitually, this sense being conveyed by the Gr. tense. Occasional acts of sin are not excluded, as we may infer from 1 John 2:1 f.
1 John 3:8. from the be ginning: as in 1 John 1:1, the remotest period of time of which we have any conception.
1 John 3:9. Paul speaks of our being risen with Christ, and, therefore, of our duty to reproduce Christ's moral perfection. John prefers to speak of conversion as a new birth, the entrance into us of a new vital principle whose product must be in accord with its essential nature.
1 John 3:10. he. brother: a return to the teaching of 1 John 2:9 f.
1 John 3:12. as Cain was of the evil one: John has been teaching that each man has a moral ancestry as well as a physical one. We are not told either here or elsewhere the condition which made Cain's works evil and Abel's righteous.