1 tn The translation of καί (kai) at the beginning of 2:3 is important for understanding the argument, because a similar καί occurs at the beginning of 1:5. The use here is not just a simple continuative or connective use, but has more of a resumptive force, pointing back to the previous use in 1:5.
sn Now. The author, after discussing three claims of the opponents in 1:6, 8, and 10 and putting forward three counterclaims of his own in 1:7, 1:9, and 2:1, now returns to the theme of “God as light” introduced in 1:5. The author will now discuss how a Christian may have assurance that he or she has come to know the God who is light, again by contrast with the opponents who make the same profession of knowing God, but lack the reality of such knowledge, as their behavior makes clear.
2 tn Grk “know him.” (1) Many take the third person pronoun αὐτον (auton) to refer to Jesus Christ, since he is mentioned in 2:1 and the pronoun αὐτός (autos) at the beginning of 2:2 clearly refers to him. But (2) it is more likely that God is the referent here, since (a) the assurance the author is discussing here is assurance that one has come to know God (all the claims of the opponents in 1:5-2:11 concern knowing and having fellowship with the God who is light); (b) when Jesus Christ is explicitly mentioned as an example to follow in 1 John 2:6, the pronoun ἐκεῖνος (ekeinos) is used to distinguish this from previous references with αὐτός; (c) the καί (kai) which begins 2:3 is parallel to the καί which begins 1:5, suggesting that the author is now returning to the discussion of God who is light, a theme introduced in 1:5. The author will now discuss how a Christian may have assurance that he or she has come to know the God who is light.
3 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.
4 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.
