Proof is simple..History is replete with noted atheists becoming believers on their deathbed. In contrast, we know of no believer that has become an atheist in the same situation.
When you see a building, you don't believe it built itself. You "know" (by implication) that there was an architect who designed it and a master builder who built it. Yet, when it comes to Creation, we have difficulty recognizing the Architect and the Master Buildier as well as the Interior Decorator.
To the best of my knowledge, there is not a single example of a house building itself. But that's precisely what atheists seem to believe in.