"Christianity claims to have the "only" answer - the only way to heaven is through him, no?"

So, what would that claim, if accurate, really matter to Atheists, anyway? Since, true Athiests, if there is such a thing (and, not infinately defined), don't believe (aka, put much stock in) there being a heaven to go to anyway...let alone a "he/she/it" to make any such such claims?

I just don't get the point of some Atheist hang ups with what others believe or don't believe (be they magic, Gods, or Santa).

However, I do see a legitimate concern for potential negative impacts of some organized religions and associated actions on societies who do bad under a religious pretense.