Four years ago, Joey Ledesma went home and told his mother, a devout Roman Catholic, that he had "returned" to Islam.
Her reaction was shock and anger; they argued and fought. In the room where he prayed, she stuck pictures of the Virgin Mary to the wall facing Mecca. A cousin asked him, "Why are you acting so crazy? You're one of us."
Mr. Ledesma, who now calls himself Yousuf, has since separated from his Catholic wife after a tug-of-war over the religious upbringing of their young son.
As his family ties frayed, Ledesma found a stronger sense of community and purpose at the mosque. In particular, he bonded with other converts, known as 'Balik Islam,' or returnees to Islam. Their shared belief is that Filipinos were originally Muslims before Spanish colonizers imposed Catholicism, so they are returning to their faith.
Lesdesma is one of an estimated 200,000 Filipinos who have converted to Islam since the 1970s, joining about 4 million Muslims from the southern Philippines who are ethnically different from the heavily Christianized areas. At first, their numbers were too small to attract much notice from authorities. That is, until Philippine security forces began focusing on the role of Muslim converts in extremist violence.
What they found was a disturbing pattern: Islamic insurgents were using cells of militant converts as terrorist operatives to strike targets in Manila. Police say a detained Balik Islam militant has confessed to planting a bomb on a ferry that killed more than 100 people in February 2004. Other detainees are linked to a foiled truck bombing in Manila that targeted the US Embassy, say officials.
Investigators say that Islamic converts can evade ethnic profiling by police, opening up a new front for groups like Abu Sayyaf that are being squeezed by US-aided military offensives in the south. "This tactical alliance [between southern insurgents and Islamic converts] will emerge to challenge the government in new ways," warns Rodolfo Mendoza, a senior police official who tracks Islamic militants.
Last month, security forces arrested Ahmed Santos, an Islamic convert and founder of the Rajah Solaiman Movement. Officials say Mr. Santos, who was arrested at a hideout on Mindanao island with his wife and five associates, was trained and financed by Al Qaeda-linked militants in the southern Philippines.
Unlike Muslims from the south, Filipino converts "blend in" with the dominant ethnic group, says a Western diplomat. "They look like every other Filipino. Abu Sayyaf members stand out."
Islamic converts have played a minor role in global terrorist plots. In 2001, Richard Reid, a British Muslim convert, was detained after he tried to detonate a bomb hidden in his shoe on a US-bound aircraft. Germaine Lindsay, a Jamaican-born convert, was one of four suicide bombers who hit London on July 7.
Officials say that while it's wrong to label all Filipino converts as potential terrorists, some factors may lead converts toward extremism. Balik Islam followers "want to prove themselves, they want to compete and not be seen as second-class Muslims," says Mendoza.
The first wave of conversions began in the 1970s when Filipinos went to work in the Middle East, a trend that continues. For some it was a way of increasing their job prospects in countries like Saudi Arabia that discriminate against Christians. Others tapped Muslim charities to help develop their communities at home. For many, it was a spiritual awakening at a time when the teachings of the dominant Catholic church were being challenged by alternative faiths.
"It's been going on for a long time but initially the rate of conversion was slow because of the majority's [negative] view of Islam. Now Filipinos are more open to other religions, not only Islam but also born-again Christianity," says Romel Banlaoi, a political scientist who has studied Balik Islam. He estimates that Islam has become the fastest-growing religion in the Philippines.
For Ledesma, the turning point came not long after Sept. 11, 2001, when he began receiving e-mails from Christian groups railing against Islam and cheering on the US-led invasion of Afghanistan. Soon after, he visited a mosque at the invitation of friends, and later converted.
"I feel more connected [now] to God than when I was a Catholic, and I practice more," he says.
Enthused, he joined a number of Balik Islam social organizations, including at least one that authorities have since shut down, citing suspected terrorist links. Ledesma came under suspicion for his role as spokesman of Fi Sabillilah, a group based in a building owned by Santos.
Ledesma says that he had never heard of the Rajah Solaiman Movement until it was identified in news reports as a terrorist group, and describes Santos as a devout Muslim who supported missionary work. He and other activists in Manila are skeptical of confessions by converts in custody; torture is common and access to lawyers is denied, they say.
In recent months, Ledesma has devoted more time to missionary work and reaching out to new converts. He's also tried to reconcile with his mother, and cites a Koranic verse about abiding respect for parents. But it's an uphill task with his family. "No matter what I do, I'm rejected," he says.