The Muslims among whom I was raised in East Africa included many who refused to pray or fast and were openly critical of religion. It would never occur to them to renounce Islam and proclaim atheism as a new identity or mission, which would have catapulted them back into a theological narrative.

In the West many of these men and women call themselves ex-Muslims and since 2007 have been organized into a loose network across more than half a dozen countries, including the United States, Canada, Britain, France, Germany and New Zealand. The identity they have chosen models the renunciation of Islam upon that of addiction, alcoholism or even crime.

By retaining “Muslim” in their name, ex-Muslims are recognizing the theological character of their renunciation. This year a young woman described her loss of faith in the North American journal The Ex-Muslim. She had been a pious believer, like many ex-Muslims, who tried to convince herself of Islam’s truth by reading the Quran and other religious texts while redoubling her devotions. Her theological reading and practice left her with unanswered questions and doubts, eventually leading her to forsake Islam.

Yet before printing and literacy made it freely available, the Quran was read by only religious authorities or recited by bored schoolboys. It was never considered a unified narrative with a single meaning and was consulted only for specific ritual, juridical or mystical purposes that required training.

But like the Bible, the Quran today is either often read to inspire belief or rejected as unbelievable, as the testimonies of faithful and faithless Muslims demonstrate. In both cases the procedure involved is identical, and indeed it appears as if it is mostly pious Muslims who become ex-Muslims. Already secular or indifferent believers are unlikely to incline toward one or the other group.

Conversion remains commonplace in the Muslim world. But while numbers are difficult to come by, conversions to Christianity are probably more than matched by internal ones between Sunni, Shia, Ahmadi and other forms of Islam in countries like Egypt and Pakistan, often involving grave risks for converts to minority sects. In Iran the Bahai Faith made deep inroads into Shiism during the 19th century. While these changes sometimes involve violence, they continue to occur and so belie the idea of an immobile Islamic society.

There is also a new movement of atheists in countries such as Saudi Arabia and Pakistan, which takes the form of secret societies. A 2012 WIN/Gallup International poll showed that 5 percent of Saudis identified as atheists — more than in the United States — while 19 percent did not consider themselves religious, in a country that punishes unbelief with death. An average of 22 percent expressed doubts about religion elsewhere in the Middle East.