Islamic terrorism? In the Philippines?

With the news today that a Canadian living in the Philippines has been kidnapped and executed by Islamist terrorists (with another Canadian remaining captive, and living on borrowed time), international terrorism has come very close to home.
John Ridsdel (the Canadian who was beheaded) and Robert Hall (who remains in captivity, and the subject of an ongoing ransom demand) were both kidnapped, along with a Norwegian man and a Filipina, on the resort island of Samal in the southern Philippines province of Davao del Norte, towards the end of last year. The kidnappings and execution were carried out by a shadowy Islamist group called Abu Sayyaf.
But I imagine that most people's reaction was, like mine, along the lines of: "Muslim terrorists in the Philippines? Isn't that a Catholic country?" So, a little research seemed in order.
So, here is the first thing to be aware of: the Philippines is a loose collection of over 7,600 islands in the western Pacific, covering about 300,000 square kilometers. The little island of Samal is about 800km, and hundreds of islands, away from the capital Manila. The country has a population of over 103 million from a whole bunch of different ethnicities. 19 main regional languages are officially recognized, in addition to the official languages of Filipino (standardized Tagalog) and English, although Ethnologue lists 186 individual languages in the Philippines, 182 of them still spoken. It is, then, a pretty disparate and heterogeneous place.
It has also had a checkered and tumultuous history of colonization, dictatorships and revolutions. In pre-colonial times, various separate nations were established under the rule of various datus, rajahs, sultans and lakans. Spanish colonization began in 1521, with all the misery that always seems to bring with it, and continued for over 300 years. The Philippine Revolution of 1896 gave rise to the First Philippine Republic. But this was short-lived, and the Philippine-American war of 1899 left the country as an American colony, which lasted until the Japanese occupation of 1942-45, and it was only in 1946 that the Philippines was finally recognized as an independent nation. Even then, though, the country had to deal with twenty years of the corrupt dictatorship of Ferdinand Marcos, the People Power Revolution of 1986, the Maguindanao massacres of 2009, various volcanic eruptions, typhoons and other natural disasters, the Asian financial crisis, etc, etc. It seems like there is never a dull moment in the Philippines.
Yes, the Philippines is a predominantly Christian country, with an estimated 83% of the population identifying as Catholic, but that percentage is gradually falling as Catholicism - largely a hangover from Spanish colonial times - gradually loosens its grip. Muslims, mainly Sunnis, are the second largest religions group, making up about 5% according to the most recent census, but as much as 11% according to the National Commission on Muslim Filipinos.
Abu Sayyaf, the Muslim terrorist group that carried out the recent kidnappings, is based in the Mindanoa region in the southwest of the Philippines. For over 30 years, it has been agitating, like the larger Moro National Liberation Front, for an independent Islamic province. Although small (an estimated 200-400 members, down from around 1,250 during its heyday in the early 2000s), the group is violent and radical. Their MO is bombings, kidnappings, assassinations and extortion, with side lines of rape, forced marriages, piracy and drug trafficking. They are most notorious for the Philippines' worst terrorist attack, the 2004 bombing of the Superferry 14, which killed 116 people. In 2014, like several other terrorist groups, they jumped on the Islamic State bandwagon, although the two organizations have no real connections. So, all in all, a small but thoroughly unpleasant terrorist group.
The rest as they say, is history. There is nothing to suggest that Abu Sayyaf is deliberately targeting Canadians, this is just business-as-usual for them.