1 John 3:7-8

Evidently the false teachers were in danger of deceiving John’s readers by telling them the opposite of what the apostles said here. John’s point was two-fold: conduct manifests spiritual relationship (cf. 1 John 2:29), and God hates sin (cf. 1 John 3:5). A sinner’s sinning has its source in the devil.

"By saying that the person who is a determined sinner (in the sense suggested by 1 John 3:6) ’belongs to the devil,’ John is in the first place drawing on the background of Genesis 3 (1-15), where the power of evil is represented as a serpent who tempts the woman (and, through her, the man) to disobey God (the reference to Cain and Abel in 1 John 3:12 confirms the suggestion that this section of the OT is in mind here)." [Note: Ibid., p. 168.]