the Syrian Observatory for Human Rights (SOHR) reported that Islamist rebels in Aleppo had executed a 15-year-old boy in front of his parents as punishment for what they regarded as a blasphemous comment.

The UK-based activist group said Mohammed Qataa was shot in the face and neck a day after being seized by the rebels, who allegedly overheard the teenager tell someone: "Even if the Prophet Muhammad comes down [from heaven], I will not become a believer."

Before executing the boy, one of the rebels reportedly told onlookers: "Disbelieving in God is polytheism and cursing the Prophet is polytheism. Whoever curses even once will be punished like this."

[Admin note:
Story has been reported differently previously. The original account, he was alleged to have refused to give free coffee to a third party. He was reported to have said "“Even if [Prophet] Mohammed comes back to life, I won’t [give coffee away]”

Thanks to John_in_Oz

Further, the translation isn't the greatest:
The Arab word for Polytheism (širk), also carries conotations of "idolatry" and "heresy". This has historic roots, or in other words, whoever translated the quote sucks at Arabic.

Thanks to UHM

Never say you didn't learn anything from here]