He's a Muslim missionary, at least according to most people. The usual denials are even broader in this story: one includes a claim that he isn't even a missionary. And of course it's an uncomfortable fact; why would someone who presumably studies the Qur'an assiduously become a terrorist? Why indeed? No satisfactory answer has ever been forthcoming from self-proclaimed moderate Muslims. From [1] Reuters, with thanks to Nicolei:

MANILA: Philippine authorities have arrested an Arab missionary who is suspected of being a member of Osama bin Laden's al-Qaeda network in the southern island of Mindanao, military officials said yesterday.

The man, Hassan al-Bakre, 55, was detained by teams of immigration and security officials on suspicion of providing funds to Muslim rebels, said Major-General Emmanuel Teodosio.

He's just teaching the basics:

The military said Hassan had made trips to Camp Omar, a rebel enclave in the Mindanao region, three months ago where he taught Arabic, Islamic studies and bomb-making.

“Based on his own accounts, more than 500 students completed the courses he had supervised,” a senior navy official, who declined to be identified, told reporters.

He said Hassan had identified five Egyptian and seven Indonesian instructors at the MILF camp.

But a rebel spokesman said Hassan was a fisherman who had lived in the area for a long time and was married to a Philippine Muslim woman.

“We have nothing to do with him,” said the spokesman, Eid Kabalu. “He's not even a missionary.”

“He's not a terrorist,” said Eid. “He's a simple-living man. People there know him to be a fisherman, not a bomb-maker.”