I'm an atheist. My parents were both atheists, as were all of my grandparents, and most of my great-grandparents (I think my father's father's family were religious). My great-grandmother was a poorly educated, menially employed working class atheist. When I was young my grandmother told me about how here mother would take charity from the Salvation Army or other religious groups and then tell her daughter that, while it was OK to accept their help, she should never presume that that meant she had to accept their ideas.
This has always made the "atheists as detached intellectuals" stereotype seem rather hollow to me - although it describes some people, I don't think it's particularly representative of atheism as a whole.
I also don't draw any distinction between various religions as groups, or particular interpretations of those groups. Neopagans and Buddhists are just as uninteresting to me as Christians or Muslims. And while I would certainly say that a member of ISIS is more likely to be a bad person than, say,
Nafez Assaily, neither is a bad Muslim, because there's no innate truth to Islamic teachings and thus no yardstick you can justificably measure them against. It would be very self-serving to say that Muslims who agree with me are "good Muslims". And the same goes for Christians, Buddhists, etc etc.
Finally, since there's people here saying there's something innately wrong with Islam, I'll agree that there's probably more "bad" Muslims than there are "bad" Christians, but in both cases we're talking about tiny groups, and this really has more to do with the relative poverty of most of the Muslim world (yes I know about Dubai, but it's an outlier) than some hidden awfulness buried in Islam. If you went back a thousand years to the Islamic Golden Age, you'd find the tables were switched. (And yes, I know that those Islamic Golden Age states had their moments of pretty reprehensible violence, but that has more to do with them being undemocratic medieval states, albeit prosperous and stable ones.)
No one has the answer to who is going to heaven or who is going to hell except God.
You should check out Calvinism.