Early on Sunday morning, a handful of Moroccans gather in a living room of an apartment on the outskirts of Casablanca. Folding their hands and closing their eyes, they pray in silence, making the sound of the traffic outside all the louder. The only word to pass their lips is a final "Amen."

The Moroccans who attend the secret mass are some of the unmentioned few, a scattered community of Christian converts who meet in homes all over the North African country. Fearing that their abandonment of Islam will draw them unwelcome attention — or even prison — their worship must be kept out of sight of the authorities.

Morocco is often perceived to be tolerant to different faiths, with the freedom of religion anchored in the 2011 constitution. Around 99 percent of the population is Sunni Muslim, but there are also around 25,000 Christians and 2,500 Jews living freely in the country.

Those Christians, however, are almost all foreigners from France, Spain and sub-saharan countries. Converted Moroccans — most of them secret worshippers, of whom there are estimated to be anywhere between 5,000 and 40,000 — face a different reality, said Zouhail, 34. "Our country has freedom of religion — but not for Moroccans," he told VICE News.

Zouhail, whose name has been changed at his request, became a Christian in 1999 at the age of 19. Three friends took him to a clandestine mass in a house used as a church, where at one point the pastor laid a hand on his head. "I felt a strong inner peace," A few months later he converted, following in the footsteps of his brother who had adopted Christianity four years earlier.

The conversion of his brother had enraged their father — an imam — and broke their mother's heart, Zouhail said. "But now my father is older and I'm stronger, it's not really a problem for him anymore."

For other people it is, however. Zouhail, an electronics good vendor from Casablanca, said that when it became known in his neighborhood that he had turned to Christianity, he was spat at in the street and soon received a visit from the police. "Two policeman questioned me, two others took notes in French and Arabic: 'Is Islam not good enough for you, did somebody pay you, or offer you a visa?' I answered: 'I just follow my heart.'"

In the country's criminal code there is no punishment for apostasy, so by law Moroccans can change faith and go to the churches — built by French and Spanish colonizers — to pray. Few of those who have converted do attend, however. "We would never prohibit anyone from entering our church, including Moroccans," Father Daniel of the Evangelical church in Rabat told VICE News. "But Moroccan society and authorities can forbid us, because by law Morocco is a Muslim country."

However, while conversion is not illegal, many can find themselves caught by a loosely worded prohibition against "shak[ing] the beliefs" of a Muslim — a crime that carries a punishment of up to three years in prison.

And that is no idle threat.

In 2010 at least seven evangelical families were expelled from the country for proselytism. In 2013, a man was sentenced to 30 months in prison for attempting to convert others in his village — an offense of which he was acquitted on appeal. And last January, police in Fes questioned a man for 11 hours, according to local news outlets, after he was found in possession of a Bible.

And then there is the fatwa that was proposed by the country's highest religious council in 2013, which called for the death penalty for Muslims who abandoned their faith. The fatwa was widely denounced, however, and has never been implemented.

But still, such a climate makes it difficult for those who have renounced their faith to step out in the open.

One of the very few to have dared to do so is Mohamed Said, 39. On Sunday mornings, he sits in the front row in the small evangelical church just off Avenue Du Far in Casablanca, whispering along with a choir of singers from Senegal, the Congo and the Ivory Coast.

A trained researcher and former Arabic student, Said converted to Christianity in 2000. With his father a moderate Muslim and his mother an agnostic, his conversion wasn't a problem to his family.

For the first four years, Said attended masses in people's houses. "But at a certain point I just didn't want to hide anymore. Muslims go to the mosque, I think I should be able to go to church," he told VICE News.

He doesn't talk much to his fellow church-goers, though, for fear of getting them into trouble. "Because the authorities might think they're the ones that converted me," Said explained. "I know the police have questioned others about me, and I have been questioned in 2010, after they confiscated my library. Now they don't hassle me anymore, as I'm quite well known."

Speaking to VICE News, long time activist Khadija Riyadi, who won a prestigious UN Human Rights prize in 2013 and is a prominent member of the Moroccan Association of Human Rights (AMDH), said of the country's Christian converts: 'They don't dare speak out, not even to their families. They celebrate mass in secret. Of course, everybody should be free to think and believe what they want. Freedom of consience is in the constitution, but the penal code hasn't been adapted to that yet. The freedom of religion basically means the freedom of being Muslim, for Moroccans."

Aicha, a Moroccan specialist on inter-faith matters who asked that her last name and exact position be withheld, told VICE News that while in principle the country provides for freedom of religion, in practice there are problems. "Converting is not forbidden, but to start a Christian school, pray openly, establish an association, organize a Christian celebration, that is problematic. It's an important debate, because it's not a good thing that Christians are praying in secret. If we want Muslims to be able to practice their faith freely in Europe, we cannot deny the rights of Christians in Muslim countries."

Morocco faced similar questions with other social changes, such as women's rights, she said. In Morocco, Aicha explained, Islamic culture is strongly anchored and people held on tightly to that, possibly fearing a loss of tradition or identity. "Well, then that fear needs to be discussed as well," she said. "What are you afraid of? That if you open the discussion on converts, a lot of people will turn christian? If you educate Muslim children about the righteousness, openness and strength of their faith, then why be afraid?"

It is that kind of thinking that gives hope to Nabil, a 45-year-old Muslim-turned-Christian from the country's south, whose name has been changed at his request. He was once an active member of Al Wadl al Ishane, Morocco's officially forbidden — but tolerated — Islamist movement, until he "started asking questions that I wasn't allowed to ask." After corresponding extensively with a theological faculty abroad, he decided to become a Christian. "I went to one of the house-churches and found out there were others like me. Until then, I thought I was alone."

Soon after, he started an association to assist the poor with healthcare, education, and social care. That attracted the attention of Islamist groups, who in turn called the police, Nabil told VICE News. "We were questioned extensively, but now we can go on with our work — as long as we remain under the radar and present ourselves as a neutral association."

That freedom to work makes Nabil optimistic about the future. Maybe one day, he said, there will be an official Moroccan church, where he and his fellow converted can freely go without problems. "I think that the government wouldn't even mind that much," he added. "But Islamic groups, neighbors, society would not accept it. Not yet."