1 John 3:12

sn Since the author states that Cain … was of the evil one (ἐκ τοῦ πονηροῦ, ek tou ponērou), in the immediate context this imagery serves as an illustration of 3:8a: The person who practices sin is of the devil (ἐκ τοῦ διαβόλου, ek tou diabolou). This is similar to John 8:44, where Jesus told his opponents “you people are from your father the devil … [who] was a murderer from the beginning.” In both Jewish and early Christian writings Cain is a model for those who deliberately disbelieve; Testament of Benjamin 7:5 looks forward to the punishment of those who “are like Cain in the envy and hatred of brothers.” It is not difficult to see why the author of 1 John used Cain here as a model for the opponents in light of their failure to “love the brothers” (see 1 John 3:17).

tn For the Greek verb σφάζω (sphazō) L&N 20.72 states, “to slaughter, either animals or persons; in contexts referring to persons, the implication is of violence and mercilessness—‘to slaughter, to kill.’ ” As a reflection of this nuance, the translation “brutally murdered” has been used.