This verse is identical with 3.24b, with the exception of three minor points: (1) The process “to abide in” is described here as reciprocal (we abide in him and he in us) but in 3.24b as one-directional. The latter may nevertheless imply reciprocity, since it continues the reciprocal expression found in 3.24a. (2) The verb “to give” is in the perfect tense rather than in the aorist in the other verse. (3) The phrase because he has given us of his own Spirit corresponds with “by the Spirit which he has given us.” These differences seem to be a matter of form rather than of contents.

In the next verses the author comes to speak of another theme, namely, the right confession based on the true Christian witness. This witness is to be found in the Church, which hands on to others the message of the eyewitnesses of Jesus’ life (see Introduction pages 6 and following).

The reason for this shift to the theme of witness is that the false teachers claim to have a testimony inspired by God’s Spirit. Therefore one must test each man’s testimony to see whether it is truly Christian (see verse 15, and compare verses 1-6). This is the case when it says that Jesus is the Christ or, in other words, that the one who has become man to save the world is God’s Son.

Quoted with permission from Haas, C., de Jonge, M. and Swellengrebel, J.L. A Handbook on The First Letter of John. (UBS Handbook Series). New York: UBS, 1972. For this and other handbooks for translators see here .