If we say that we have fellowship with Him and yet walk in the darkness [of sin], we lie and do not practice the truth;

And yet I *am* giving you a new command, for such it really is, so far as both He and you are concerned: because the darkness is now passing away and the light, the true light, is already beginning to shine.

adhere therefore to what ye have learnt from the beginning. if you adhere to what ye have heard from the beginning, you will still persist to own both the son and the father.

This Jesus is the one whose coming [to earth was introduced] by water [at His immersion. See Matt. 3:13] and [completed] by blood [at His crucifixion, John 19:17-37]. He did not come by the water only, but by the water and by the blood. And it is the Holy Spirit who gives testimony [at both of these events], because the Holy Spirit is [always] the truth. [See John 16:13].