Islam is often perceived as a religion antithetical to British, secular values. But between 2001-2011, more than 100,000 British people converted to Islam. This may come as a surprise, especially considering the virulent climate of Islamophobia supposedly pervading the country in the shadow of 9/11. Yet, while Muslims may rejoice at the news of many British people flocking to Islam, little is known about the large proportion of converts who later become apostates.

“Many converts leave the faith. We don't have exact statistics but some stats say 50 per cent will leave within a few years,” says Usama Hasan, a part-time Imam and a senior researcher at the counter extremism think-tank, the Quilliam Foundation.

The internet, in particular, Twitter, provides ex-Muslims, often with pseudonymous accounts, a safe haven to challenge, criticise and mock Islam. The Council of Ex-Muslims of Britain (CEMB), founded six years ago, was set up by a group of non-believers and acts as a community for those who have renounced their faith.

There are, of course, a multitude of reasons why someone might become an apostate after converting. Many British women convert when marrying a Muslim man, but, when the relationship ends, they sometimes leave the faith. (The same rarely happens in reverse, as the consensus of scholars believes a Muslim woman marrying a non-Muslim man is against the Sharia.) Some converts don’t receive the community support upon entering the faith. While others can be referred to as “drifters”: they experiment with different lifestyles. However, many ex-Muslims cite bad experiences with Muslims in their stories of how they came to renounce the faith.

Pepe, 39, is an ex-Muslim who was born in London but now lives in Canada with his Muslim wife and two children. He converted at 20, after discovering the religion through Sufism, the mystical dimension of Islam. He remained a fairly practising Muslim for 15 years but he often struggled with certain aspects of the faith, which he shrugged off as “satanic thoughts”.

In his early 30s he became disillusioned with the hardline views held by many Muslims and joined the Chisti Tariqah, a Sufi Order originating from Afghanistan.

He agrees to an interview over Skype from his home. “The more I got involved with the Tariqah, the more cult-like it was becoming. I had to get permission from the Sheikh [religious teacher] to do a lot of things, like if I wanted to leave town. When I questioned things, they told me to completely stop reading books and only read what they gave me,” he says.

After his Sheikh interpreted one of Pepe’s dreams to suggest that his father didn’t care about him, he became disaffected with the Tariqah and soon left the faith altogether.

“I was confused when I first left the religion but I came to the conclusion that none of it is real. I was very angry at the time,” he says.

“I would call myself an atheist but even if there is a higher power, I don’t think it affects the way I am with people. If anything, I would say I’m a more compassionate person now, because I know how people’s minds can be manipulated,” he says.

How has it affected his marriage? “When my wife married me, she married a Muslim guy, so I don’t stop her from teaching Islam to our kids,” he says. “We have a deal: I don’t eat pork or drink alcohol in the house or in front of the kids. And I can’t tell my wife’s parents that I have become an apostate because they are orthodox and would see the marriage as annulled.”

Other ex-Muslims, however, paint a slightly brighter picture of the religion. Goran Miljević, 19, from London, converted in 2010 after being kicked out of college. “Converting to Islam was somewhere I could belong, a brotherhood, somewhere you can go where you’re listened to and supported,” he says.

Miljević comes from a Serbian Christian family and when he converted, his parents were angry. “My father thought I was joking. I slept at the Mosque for a couple of nights because my parents were so upset with me. If I wasn’t so young, my parents would have kicked me out the house,” he says.

“I was really practising at one point, proper hard core. But what I realised is that you can’t be a convert and be moderate, you have to be extreme because that’s how you distinguish yourself,” he says.

However, after three months of being a Muslim and feeling the disapproval from his family, Miljević realised Islam wasn’t for him. “Even though I left the faith, I know Islam isn’t what people think. I will even correct people who think of Islam in a certain negative way. It’s a good religion but at the end of the day, religion is politics. People like bin Laden and Anjem Choudary use the religion to stir people and make them do things,” he says.

75 per cent of all British converts to Islam are women. And, according to one study in Leicester, Between Isolation and Integration, a large percentage of female converts were attracted to the faith because of the status it affords them. Many believe the religion provides them with a high spiritual status and a type of dignity our modern, secular country can’t.

But, the majority of British women who convert report feeling confused due to the conflicting ways Islam is introduced to them. “The reason why some converts leave the faith or become confused is not only because of the narrow-mindedness of many Muslims. But also because of the dominance of culture: some Muslims will insist on Pakistani, Saudi or Iranian culture and say it is Islamic,” says Usama Hasan.

It is not just converts who are leaving the faith but also Muslims born into the faith. “I've noticed certainly after 9/11 that a growing number of young Muslims in the UK have lost their faith, and many have become Christian, Buddhist, agnostic or atheist,” Hasan says.

While many apostates travel a lonely path once leaving the faith, as friends and family often marginalise them, far too many also feel the rage of Muslim extremists.

Saif Rahman is the author of The Islamist Delusion: From Islamist to Cultural, Humanist Muslim. He was born to a Muslim family of Pakistani-Indian origin but abandoned Islam around a decade ago. He now regularly criticises Islam. It comes at a wretched price: he has received almost 150 death threats in the past five years.

“9/11 was a critical moment for many ex-Muslims,” says Rahman, “We felt we could no longer relate to these people [the terrorists],” he says over the phone.

“The death threats used to get to me but once you cross the 100 mark, it becomes a bit of a joke. Some are so ludicrous. I’m one of the biggest figureheads for the hate. But because they’re done by the net, I can be a bit more blasé about them,” he says.

Some Islamic scholars believe that apostates should be killed, especially if they go on to attack the faith, and cite as evidence a couple of Prophetic sayings in Islam. However, there is no Quranic justification for this stance and other scholars believe that killing apostates is a pre-modern tradition that no longer applies today.

Although Rahman regularly attacks Islam on Twitter, he concedes that there is much “beauty” in the religion. “I do think Islam is a bad religion but I’m not blinded to its beauty. Some of the sayings of the Prophet Muhammad leave me teary-eyed. I would even argue that the sense of family, hospitality and other ethical values are actually Islamic,” he says.

The Council of ex-Muslims recently tweeted: “The internet has made our voices louder, for the first time in history ex-Muslims can speak freely, by-passing death, fear, blasphemy [and] taboos.”

But do ex-Muslims have the right to mock religion? Faith, after all, gives people meaning, hope and provides answers to existential questions. Helen, an ex-Muslim from Scotland, who says she was forced to convert to Islam and later mistreated by the family believes it is a good thing to mock religion. “The truth will push you off before it sets you free. People have to toughen up, instead of relying on an imaginary deity to give them meaning,” she says.

Pepe says many ex-Muslims behave with a kind of reactive defiance once apostasising. “People who left the religion at the angry stage, they want to hit back at it, to kind of feel some kind of satisfaction. But when they do it too much it just has a negative effect overall.”

Usama Hasan, however, is hopeful for the future of Islam, despite the threat of ex-Muslims. “On a positive note, I have come across Muslims who have lost their faith but regained it after they have come across different interpretations, deeper, wider and more generous of the Quran and Prophetic traditions which accord well with the modern world,” he says. “It’s up to the people of knowledge to dig those interpretations out. And once they provide those insights people are attracted back to the faith because faith is something beautiful. God is beautiful and He is loving and merciful and waiting to be discovered and known,” he adds.

For some, Islam manifests itself as a religion of beauty and peace, either when people convert to the faith or when they discover the “different interpretations”. But, for far too many, especially those with bad experiences with Muslims, the religion reveals itself to be the way Islamophobes negatively caricature it to be.