In John’s Gospel (the ninth chapter), Jesus asks the blind man he’s just cured whether he ‘believes’ in the Son of Man. He’s certainly not asking (as he might about the Loch Ness monster) whether the man is of the opinion that the Son of Man exists; he wants to know whether the former blind man is ready to trust the Son of man – that is, Jesus in his role as representative of the human race before God. The man – naturally – wants to know who the ‘Son of Man’ is, and Jesus says that it is him; the man responds with the words, ‘I believe.’
He believes; he has confidence. That is, he doesn’t go off wondering whether the Son of Man is out to further his own ends and deceive him. He trusts Jesus to be working for him, not for any selfish goals and he believes that what he sees and hears when Jesus is around is the truth. Hence the radical difference from ‘believing’ in UFOs or the Loch Ness monster. To believe in these doesn’t make that much difference to how I feel about myself and the world in general, and it has nothing to do with whether the Loch Ness monster is reliable or not. If it existed, it would undoubtedly be useful to know if it was a creatures of dependable and regular habits, but that isn’t what we have in mind when we talk about believing in it.
Rowan Williams, Tokens of Trust, pp. 5-6
Locus Communis 