I've recently been formulating a new ( and not very) scientific theory which I call the Theory of Relative Weirdness.
The way the theory works is simple: if the weirdness level of something that might exist is similar to that of something that definitely does exist, there's a possibility it might exist too. The yeti and the sasquatch, for example, have equal weirdness to gorillas and other apes, and therefore might exist. The Mongolian Death-Worm isn't that much weirder than an electric eel and therefore, though unlikely, there's perhaps a tiny chance that it might exist too. God, meanwhile, is so massively less weird than what we know for a fact is true about how the universe works that his existence is very, very unlikely indeed.