1 tn Grk “the one saying he is in the light and hating his brother.” Here καί (kai) has been translated as “but” because of the contrast present in the two clauses.
2 tn Grk “his brother.” Here the term “brother” means “fellow believer” or “fellow Christian” (cf. BDAG 18 s.v. ἀδελφός 2.a). In the repeated uses of this form of address throughout the letter, it is important to remember that sometimes it refers (1) to genuine Christians (those who have remained faithful to the apostolic eyewitness testimony about who Jesus is, as outlined in the Prologue to the letter, 1:1-4; an example of this usage is 2:10; 3:14, 16), but often it refers (2) to the secessionist opponents whose views the author rejects (examples are found here at 2:9, as well as 2:11; 3:10; 3:15; 3:17; 4:20). Of course, to be technically accurate, in the latter case the reference is really to a “fellow member of the community”; the use of the term “fellow Christian” in the translation no more implies that such an individual is genuinely saved than the literal term “brother” which the author uses for such people. But a translation like “fellow member of the community” or “fellow member of the congregation” is extremely awkward and simply cannot be employed consistently throughout.
3 sn The one who hates his fellow Christian. The author’s paradigm for the opponents portrays them as those who show hatred for fellow Christians (Grk “brothers,” but not referring to one’s physical siblings). This charge will be much more fully developed in chap. 3, where the author will compare the opponents to Cain (who is the model for one who hates a brother, since he ultimately murdered his own brother). In 1 John 3:17 the specific charge against the opponents will be failing to give material aid to a brother in need.
4 sn 1 John 2:3-11. The section 2:3-11 contains three claims to intimate knowledge of God, each introduced by the phrase the one who says (participles in the Greek text) in 2:4, 6, and 9. As with the three claims beginning with “if” in the previous section (1:6, 8, 10), these indirectly reflect the claims of the opponents. Each claim is followed by the author’s evaluation and its implications.