Commenting on this passage, Martyn Lloyd-Jones wrote the following.
The gospel is a declaration, a manifestation, a showing. ... The trouble with so many of us (is that) we persist in regarding it as an outlook, as something which results from the meditation and thought of man on the whole problem of life and living. That has been the real tragedy of the last century or so, when philosophy took the place of revelation and people said that the Bible is nothing after all but human thoughts, man's ideas, man's search after God.
But that is not the gospel! The whole position of the Apostles, John and the rest, is that they have something to declare, something to say. They have seen something, they are reporting it, and that something is so wonderful that John can scarcely contain himself. ...There is nothing uncertain about this message, it is a proclamation; there is an urge and an authority behind it.
I know that the old charge which has so often been brought up against the Church and her preachers is that we are dogmatic; but the preacher who is not dogmatic is not a preacher in the New Testament sense. We should be modest about our own opinions and careful as to how we voice our own speculations, but here, thank God, we are not in such a realm, we are not concerned about such things. What we do is not to put forward a theory which commends itself to us as a possible explanation of the world and what we can do about it; the whole basis of the New Testament is that here is an announcement, a proclamation - those are New Testament words.
The gospel, according to the New Testament, is a herald; it is like a man with a trumpet who is calling people to listen. There is nothing tentative about what he has to say; something has been delivered unto him, and his business is to repeat it. ...We are ambassadors, and the business of the ambassador is not to say to the foreign country what he thinks or believes; it is to deliver the message which has been delivered to him by his home government and the King he represents. That is the position of these New Testament preachers, and that is how John puts it here - 'I have an amazing thing to reveal,' he says.