The evidence for aliens is Earth. Our planet has proven that when certain conditions are met, life exists. Given the number of stars, planets and habitable zones in space, It seems virtually impossible for Aliens not to exist. I just highly doubt any have traveled to Earth (even highly advanced technology can't go faster than the speed of light, as far as I know). More likely than not, I suspect humans will be the first aliens to land on a different world with life and, unfortunately, we'll probably be bad for their ecosystem (The movie Avatar is very much how I picture it happening, minus the happy ending.) As for god; no evidence has been found at all. One could cite miracles, but given the fact that they are largely based on a single person's experience, which cannot be tested or proven, they can't be used as evidence (in much the same way that alien sightings can't be used as evidence for aliens).