[5:2] 1 tn Once more there is the familiar difficulty of determining whether the phrase refers (1) to what precedes or (2) to what follows. Here, because ἐν τούτῳ (en toutw) is followed by a clause introduced by ὅταν (Jotan) which appears to be related, it is best to understand ἐν τούτῳ as referring to what follows. The following ὅταν clause is epexegetical to ἐν τούτῳ, explaining how we know that we love God’s children: “by this we know that we love God’s children, whenever we love God and keep his commandments.”
[5:3] 2 tn The force of the γάρ (gar) at the beginning of 5:3 is similar to another introductory formula used by the author of 1 John, καὶ αὕτη ἐστίν (kai Jauth estin; used in 1:5; 5:4, 11, and 14). The γάρ draws an inference based on the preceding statements, particularly the one in 5:2b, regarding the love of God. If in 5:2 loving God and keeping his commandments is the key to knowing that we love God’s children, it is important to define what the love of God involves, and this is what the author is doing in 5:3. In fact, as the following ἵνα (Jina) clause makes clear, loving God consists in keeping his commandments.
[5:3] 3 tn Once again the genitive could be understood as (1) objective, (2) subjective, or (3) both. Here an objective sense is more likely (believers’ love for God) because in the previous verse it is clear that God is the object of believers’ love.
[5:3] 4 tn Contrary to the punctuation of NA27 and UBS4, it is best to place a full stop (period) following τηρῶμεν (thrwmen) in 5:3. The subordinate clause introduced by ὅτι (Joti) at the beginning of 5:4 is related to the second half of 5:3 which begins with καί (kai). Καί is commonly used by the author to begin a new sentence, probably by analogy with the Hebrew vav consecutive.
