'Omar, named after one of Islam's most revered caliphs, has rejected the faith of his forefathers. He is one of the founding members of an online group - a meeting point for the atheists of Pakistan.
But even there he must stay on his guard. Members use fake identities.
"You have to be careful who you are befriending," he says.
One man contacted Omar to say he had visited his Facebook profile and printed out pictures of him with his family. "You cannot be safe," Omar says.
In Pakistan, posting about atheism online can have serious consequences.
Under a recently passed cyber-crime law, it is now illegal to post content online - even in a private forum - that could be deemed blasphemous.
The government took out adverts in national newspapers asking members of the public to report any content they believe could constitute blasphemy.
And the law is being enforced. In June this year, in the first case of its kind, Taimoor Raza was sentenced to death for posting blasphemous content on Facebook. ...'