Someone who can't answer the question "Why did God create Smallpox?", or, just rationalize it in some weird way in favour of their God.
Atheist Vs Christian debate
Christian: You're going to Hell!
Atheist: Okay that's nice but can you answer the question I've asked 9 times; Why did your God create Smallpox?
Christian: Disease is a result of Sin!
Atheist: So why would a merciful God punish millions of humans, many being babys, because some guy was convinced by a talking snake to eat a magical apple that your God put there in the first place? And that's just one of God's many creations that he made in his infinite wisdom.
Christian: Umm..Uhh... EVOLUTION IS JUST A THEORY..and..and.. YOU'RE A DIRTY COMMUNIST SOCIALIST NAZI GAY HOMO FAG FAG!