1 Yohanes 3:10

3:10 By this ¹  the children of God and the children of the devil are revealed: Everyone who does not practice righteousness – the one who does not love his fellow Christian ²  – is not of God.

1 Yohanes 5:2

5:2 By this ³  we know that we love the children of God: whenever we love God and obey his commandments.

[3:10]  ¹ tn Once again there is the problem (by now familiar to the interpreter of 1 John) of determining whether the phrase ἐν τούτῳ (en toutw) in 3:10 refers (1) to what precedes or (2) to what follows. If it refers to what precedes, it serves to conclude the unit which began with 2:28. The remainder of 3:10 would then form a transition to the following material (another “hinge” passage). On the other hand, if the phrase ἐν τούτῳ refers to what follows, then the entirety of 3:10 is a summary statement at the end of 2:28-3:10 which recapitulates the section’s major theme (conduct is the clue to paternity), and provides at the same time a transition to the theme of loving one’s brother which will dominate the following section (3:11-24). Although R. E. Brown (Epistles of John [AB], 416) prefers to see the phrase as referring to the preceding material, it makes better sense to refer it to the remainder of 3:10 that follows, and see the entirety of 3:10 as both a summary of the theme of the preceding section 2:28-3:10 and a transition to the following section 3:11-24.

[3:10]  ² tn See note on the term “fellow Christian” in 2:9.

[3:10]  sn Does not love his fellow Christian. The theme of loving one’s fellow Christian appears in the final clause of 3:10 because it provides the transition to the second major section of 1 John, 3:11-5:12, and specifically to the following section 3:11-24. The theme of love will dominate the second major section of the letter (see 1 John 4:8).

[5:2]  ³ 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.”