Yeah, my dad's kinda the same way, except he tries to bring in things like entropy to explain how we couldn't have simply, for lack of a better term, happened. Can one prove that gods don't exist? As one can't prove a negative, no. However, you must ask the converse...can you, using verified, peer-reviewed scientific evidence prove the existence of any deific force enacting its will over our lives in any meaningful way? As far as science has been able to find, no, there is not.
The universe is governed by natural laws that require no intelligence to keep in motion, they perpetuate themselves quite fine on their own, like gravity. What got these laws in motion in the first place? That's like asking what happened before the universe was, its a question that, for now, we simply can't answer. We lack the knowledge, technology, and perspective to make a precise judgment on such a thing.
Religion is, to me, a way to fill in the gaps science hasn't filled in yet, it (rather conveniently) explains that which has yet to be explained. Its not unexplainable, its not unknowable. People thought the sun was unknowable, and now, we can harness the very force that governs its burning (nuclear fusion) to obliterate entire cities in the blink of an eye.
Really, if you ask me, it comes down to how a person answers a question that they can't give an adequate answer to: the religious man says, "god did it." The scientist says, "I don't know, but we're working on it."
In the end, we're human. Its in our nature to seek an explanation behind the workings of ourselves, our world, and the universe at large. We're incredibly curious, but we've got that matched by a remarkable ability to answer questions no other species on the planet has the capacity to even know to ask. Some seek out religion, some use science...some use both. We must explain, we must know. Mysteries don't last long around a human.