If the guy didn't ever just randomly ridicule you for your believs BUT if you asked him what he thought on it he would tell you in a clear but respective what that he thinks your believes are ridiculous to him
Maybe... depends on who he is. I don't like the idea of a person calling another person's belief system words like "ridiculous." in my opinion that's just a sign of disrespect for no reason, and it's generally a type of personality I'm not attracted to. A religious person can be like this too, and I wouldn't like it. If this atheist dude found a particular extreme behavior like waging war in the name of religion ridiculous, that's okay... I understand that.
Personally, I have ran into problems with differing opinions on religion in relationships. Even if people agree to disagree, I feel like it will be a big obstacle down the road if the relationship becomes more serious (ex. sex until marriage, how children are raised, religious practices, family may disagree, etc)
I'm agnostic and I said maybe cause it would depend on if he's nice about it. Even though I'm not religious or anything like that I have been picked on by atheists just because I won't choose between theism and atheism.