Albert Barnes Commentary 1 John 4:14

"And we have beheld and bear witness that the Father hath sent the Son [to be] the Saviour of the world." — 1 John 4:14 (ASV)

And we have seen. See Barnes' notes on 1 John 1:1.

And do testify. See Barnes' notes on 1 John 1:3.

That is, we who are apostles bear witness to you of this great truth, that God has sent his Son to be a Saviour. Compare to John 20:31 (see Barnes' notes).

The reason why this is referred to here is not quite apparent, but the train of thought in this passage would seem to be this: The writer is speaking of the love of God, and of its manifestation in the gift of the Saviour, and of the proper influence which it should have on us.

Struck with the greatness and importance of the subject, his mind turns to the evidence on which what he was saying rested—the evidence that the Father had really thus manifested his love. That evidence he repeats, that he had actually seen him who had been sent, and had the clearest demonstration that what he deemed so important had really occurred.