Atheists, tell me, a Roman Catholic: why should I become an atheist?

[Tonus]

The difference between saying God has always been here and saying something in nature has always been here is that God is supernatural. That's the whole point of God - a being that is beyond our natural world and its laws. The laws of nature, as far as we know, state that everything has a beginning. Just as there is no "proof" of God, neither is there "proof" that anything in nature can be infinite, having no beginning. Either way you're taking somewhat of a leap of faith by making either claim.

I am not making that claim, though. I am admitting that I don't know what the answer is. I am also pointing out that if someone is going to offer an answer, they cannot simply make up something that they cannot demonstrate or prove.

Let's say we don't know how the universe came to exist. Based on what we know, it had a beginning. And it makes sense to us that anything that had a beginning must have a cause. My answer to that is... I don't know what that cause is because we don't have enough information or knowledge. We can make guesses, but there is no evidence to corroborate any of our ideas. Someone comes along and insists that since people make watches, there must have been an intelligence that caused the universe to begin. He calls this intelligence "God" and then goes on to define him in a fair amount of detail. He has no evidence for his claim, he's just filling in the blanks with his imagination.

He is taking a leap of faith. I am not. I am waiting on more knowledge and understanding before I go any further than "I don't know." Because when we didn't know what caused lightning, that guy's explantion ("it was god") was wrong. When we didn't know anything about diseases, that guy's explanation ("it's demons") was wrong. When we didn't know enough about the cosmos, that guy's explanation ("the sun revolves around the earth") was wrong. The only thing that guy has going for him is that his legs are much stronger than mine, on account of all of that leaping that he's been doing for the past several centuries.