Finally he told his parents, both devout Muslims, that he was an atheist. They brought home clerics to talk with him, trying in vain to bring him back to the faith. Finally, they gave up.

"It was the domino effect — you hit the first pin and it keeps on going and going," Said Awad, 23, who grew up in the United Arab Emirates and lives there. "I thought: It doesn't make sense anymore. I became a new person then."

An openly self-described atheist is an extreme rarity in the Arab world, where the Muslim majority is on the whole deeply conservative. It's socially tolerated to not be actively religious, to decide not to pray or carry out other acts of faith, or to have secular attitudes. But to outright declare oneself an atheist can lead to ostracism by family and friends, and if too public can draw retaliation from Islamist hard-liners or even authorities.

Still, this tiny minority has taken small steps out of the shadows. Groups on social media networks began to emerge in the mid-2000s. Now, the Arab Spring that began in early 2011 has given a further push: The heady atmosphere of "revolution" with its ideas of greater freedoms of speech and questioning of long-held taboos has encouraged this opening.