An Atheist who has absolutely no patience for religious people, mainly Christians. They will talk crap about Christians all day, then get super pissed when anybody says a thing about Atheism, or even just stands up for their own religion. About 30% of Atheists are also Asstheists, and generally give the respectable Atheists a bad name.
Being Atheist is cool, being Asstheist is not.

The only reason you should Thumbs-Down this definition is if you are an Asstheist.
by Slayn June 17, 2007
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One who argues for the well-supported position of atheism in a manner most ass.
Richard Dawkins: 'You, sir, are a bumbling idiot. EEEEvolution and God do not coincide."

Creationist: "I don't understand anything about anything, but you're quite the asstheist."
by Armchair Academic September 07, 2016
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