Where does the idea of God come from?… Early man is, like everything else, an evolved creature and he finds himself in a world that he’s begun to take a little charge of; he’s begun to be a tool-maker, a changer of his environment with the tools that he’s made…. Tools have enabled us to think intentionally, to make things and to do things to create a world that fits us better. Now imagine an early man surveying his surroundings at the end of a happy day’s toolmaking. He looks around and he sees a world which pleases him mightily: behind him are mountains with caves in them—mountains are great because you can go and hide in the caves and you are out of the rain and the bears can’t get you; in front of him there’s the forest—it’s got nuts and berries and delicious food; there’s a stream going by, which is full of water—water’s delicious to drink, you can float your boats in it and do all sorts of stuff with it; here’s cousin Ug and he’s caught a mammoth—mammoths are great, you can eat them, you can wear their coats, you can use their bones to create weapons to catch other mammoths. I mean this is a great world, it’s fantastic. But our early man has a moment to reflect and he thinks to himself, ‘Well, this is an interesting world that I find myself in,’ and then he asks himself a very treacherous question, a question which is totally meaningless and fallacious, but only comes about because of the nature of the sort of person he is, the sort of person he has evolved into and the sort of person who has thrived because he thinks this particular way. Man the maker looks at his world and says, ‘So who made this then?’ Who made this?—you can see why it’s a treacherous question. Early man thinks, ‘Well, because there’s only one sort of being I know about who makes things, whoever made all this must therefore be a much bigger, much more powerful and necessarily invisible, one of me and because I tend to be the strong one who does all the stuff, he’s probably male.’ And so we have the idea of a God. Then, because when we make things we do it with the intention of doing something with them, early man asks himself, ‘If he made it, what did he make it FOR?’ Now the real trap springs, because early man is thinking, ‘This world fits me very well. Here are all these things that support me and feed me and look after me; yes, this world fits me nicely’ and he reaches the inescapable conclusion that whoever made it, made it for him.
This is rather as if you imagine a puddle waking up one morning and thinking, ‘This is an interesting world I find myself in—an interesting hole I find myself in—fits me rather neatly, doesn’t it? In fact it fits me staggeringly well, must have been made to have me in it!’ This is such a powerful idea that as the sun rises in the sky and the air heats up and as, gradually, the puddle gets smaller and smaller, it’s still frantically hanging on to the notion that everything’s going to be alright, because this world was meant to have him in it, was built to have him in it; so the moment he disappears catches him rather by surprise.”
Douglas Adams, “Is There An Artificial God?”