Is it wrong that a reject a guy only because he is atheist?

While he does sound perfect for you, if you're really religious I can see why it would be important for you to be with someone who shares your faith. There are just some differences you can't compromise on, no matter how great your potential boyfriend or girlfriend seems otherwise. With you, it's the difference in religion (or the lack of it). If your faith is that important to you that you need to be with someone who shares it or at the very least some branch of it (which is already pretty flexible on your part if he doesn't have to be Catholic all the way in order for him to stand a chance), then I don't think you did wrong by it. It would be worse if you agreed to be with him only to end up pressuring him to conform to your religion somewhere down the road because you can't get over the fact that he's an atheist and doesn't want to change that fact.