Theists: Atheism is a totally new phenomenon. If it weren't we'd have historical evidence of it!
Me: You mean like Diagoras of Mellos in 5th century BCE, that one Ancient Roman tombstone*, Omar Khayyam in 1100s Iran, Menocchio in 1500s Italy, Giulio Cesare Vanini in 1619, Kazimierz Łyszczyński in 1600s Poland, Thomas Aikenhead in 1600s Scotland, and Percy Shelley in 1817?
Theists: Um...
Me: Moreover, do you know what all but 2 of these 8 examples have in common? They were all persecuted for being atheists. Atheists only show up in large numbers in history recently because before it wasn't safe to come out.
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* "Do not pass my epitaph, traveller
But having stopped, listen and learn, then go your own way
There is no boat in Hades, no ferryman Charon
No caretaker Aiakos, no dog Cerberus
All we who are dead below
Have become bone and ashes but nothing else
I have spoken to you honestly, go on traveller
Least even while dead I seem talkative to you"