I'm pretty sure I'm about to /thread this, but this was an argument that was presented towards me that god existed(I was pretty open about my atheism and some people, such as this person, took offence to it and tried to convert me, without success). I'm not singling out religious groups here, as I'm pretty sure that even the most fundamental religious types will facepalm at this. Anyways, here it is:
The reason the sky is blue is because there was once water in a shell around the Earth, but a hole was formed- which we now think is the ozone layer- and as a result, the earth flooded, and that caused Noah's flood. But the water has been evaporating and returning up and reforming the shell so that's why the world isn't flooded anymore. And because water is blue, and we can see it in the sky, that's why the sky is blue. But nothing could have created that hole except for a God, so therefore god exists.
That was the gist of it but it was several years ago, so I can't remember the exact words and logic he used- it's probably a repressed memory due to the pain that it caused to my brain- but that night I cried for the future of humanity. The same guy presented me with other stuff that was almost as bad, but nothing that sticks out like this did.