Why can't my friend accept this?

It is sad that she cannot accept these differences, but the truth is that friends often drift apart as they get older. I have experienced this on more than one occasion. In time you will find that your best friends are those who you have the most in common with. maybe you will be able to get through this, but the truth is some people are just intense about religion. I have found myself curious in these sorts of things as well, but if she is being so rude there's not much you can do other than to sincerely ask her to lay off. You need to make it clear that she needs to accept your personal beliefs even if she doesn't believe in them.