The Syrian Observatory for Human Rights said the boy had been arguing with someone about the existence of God, and was heard to say: "Even if the Prophet Mohammad returns, I will not become a believer."
But other sources suggested that the comment was misheard, and that the boy was actually arguing with another customer over giving him a free coffee, saying "Even if the Prophet returns, I will not give you a free coffee."
Qataa was reportedly abducted and tortured for 24 hours, before being dragged into the middle of a crowded street and executed in front of his mother.
It was quite explicit that he was murdered for atheism.
The Observatory said in a statement: “People gathered around him and a member of the fighting brigade said: ‘Generous citizens of Aleppo, disbelieving in God is polytheism and cursing the prophet is a polytheism. Whoever curses even once will be punished like this’.
“He then fired two bullets from an automatic rifle in view of the crowd and in front of the boy’s mother and father, and got into a car and left.”
I curse that cowardly gunman’s god a thousand times, and I won’t give him any free coffee, either.
Mohammad Qataa was 15 years old, and killed for being smarter than a pious thug.