C. S. Lewis mentions this in 'Mere Christianity". At the end of Chapter 3 he says: "I am trying to prevent anyone saying the really foolish thing that people often say about Him: 'I'm ready to accept Jesus as a great moral teacher, but I don't accept his claim to be God.' That is the one thing we must not say. A man who was merely a man and said the sort of things Jesus said would not be a great moral teacher. He would either be a lunatic - on the level with the man who says he is a poached egg - or else he would be the Devil of Hell. You must make your choice. Either this man was, and is, the Son of God: or else a madman or something worse. You can shut Him up for a fool, you can spit at Him and kill Him as a demon; or you can fall at His feet and call Him Lord and God. But let us not come with any patronising nonsense about His being a great human teacher. He has not left that open to us. He did not intend to."
Chapter 4
"We are faced then, with a frightening alternative. This man we are talking about either was (and is) just what He said or else a lunatic or something worst. Now it seems obvious that He was neither a lunatic nor a fiend: and consequently, however strange or terrifying or unlikely it may seem, I have to accept the view that He was and is God."
Now, the words of Jesus were not written down by him or by one man, but by several men, which makes it more believable than if only one man had written it. The Gospel of John, chapter 1 says well who Jesus was:
"In the beginning was the Word; the Word was in God's presence, and the Word was God. He was present to God in the beginning. Through him all things came into being, and apart from him nothing came to be. Whatever came to be in him, found life, life for the light of men. The light shines on in darkness, a darkness that did not overcome it.
There was a man named John sent by God, who came as a witness to testify to the light, so that through him all men might believe - but only to testify to the light, for he himself was not the light. The real light which gives light to every man was coming into the world.
He was in the world, and through him the world was made, yet the world did not know who he was. To his own he came, yet his own did not accept him. Any who did accept him he empowered to become children of God.
These are they who believe in his name - who were begotten not by blood, nor by carnal desire, nor by man's willing it, but by God.
The Word became flesh and made his dwelling among us, and we have seen his glory: the glory of an only Son coming from the Father, filled with enduring love."