Hey, I agree with what wedrifid said. I fell in to the same trap of trying to beat religious nonsense out of people as a kid. It's a very sexy thing to think about but it doesn't really get you anywhere, in my experience. My only additional advice is that you consider trying to make your "recapitulation" to Christianity convincing. For example, don't give in right away, and make up a story for where you went wrong and why you're a Christian again, e.g. "I thought that x, but now I see that y and z, so x is wrong. I guess maybe God exists after all."

Something to keep in mind when arguing with your dad (internally only): your dad is presenting you with evidence and arguments in favor of God's existence, but these amount to a biased sample. If you really want to know the truth, you should spend an equal amount of time hearing arguments from both Christians and atheists, or something like that.

Also, you can check internally if any of his arguments hold up to this test: http://commonsenseatheism.com/?p=8854