1 John 5:8

5:8 the Spirit and the water and the blood, and these three are in agreement.

1 John 5:6

5:6 Jesus Christ is the one who came by water and blood – not by the water only, but by the water and the blood. And the Spirit is the one who testifies, because ¹  the Spirit is the truth.

1 John 1:7

1:7 But if we walk in the light as he himself is in the light, we have fellowship with one another and the blood of Jesus his Son cleanses ²  us from all sin. ³ 

[5:6]  ¹ tn This ὅτι (Joti) is best understood (1) as causal. Some have taken it (2) as declarative, giving the content of the Spirit’s testimony: “and the Spirit is the One who testifies that the Spirit is the truth.” This is certainly possible, since a ὅτι clause following the cognate verb μαρτυρέω (marturevw) often gives the content of the testimony (cf. John 1:34; 3:28; 4:39, 44). But in the Gospel of John the Spirit never bears witness on his own behalf, but always on behalf of Jesus (John 15:26, 16:13). There are, in fact, some instances in the Gospel of John where a ὅτι clause following μαρτυρέω is causal (8:14, 15:27), and that is more likely here: “and the Spirit is the One who testifies, because the Spirit is the truth.”

[1:7]  ¹ tn Or “purifies.”

[1:7]  ² tn BDAG 50 s.v. ἁμαρτία 1 defines this term as “a departure fr. either human or divine standards of uprightness” (see 1 John 5:17 where ἁμαρτία [Jamartia] and ἀδικία [adikia] are related). This word occurs 17 times in 1 John, of which 11 are singular and 6 are plural.