The BisayanA.– In my research I found no evidence that Datu Lapu-lapu was a Muslim, except for unsubstantiated claims without provenance. On the other hand, there is ample evidence that tend to disprove that he was a Muslim; viz:
1. Ancient Bisayan people, which included Lapu-lapu’s tribe in the 15th century, were called pintados by the Spaniards because they wore tattoos in their bodies, according to historical sources, among them the Boxer Codex (1590a.).
But Muslims consider permanent tattoos to be haram or forbidden by Islamic law, based on an oral tradition (hadith) of the Prophet Muhammad.

2. During paganito rituals invoking the spirits of nature for fertility of crops, newlyweds, or for rains, ancient Bisayans use pigs as sacrificial offerings, which were later cooked and eaten in a feast.
But Muslims are prohibited from eating pork. The holy Quran itself prohibits the consumption of pork in many of its verses.

3. An entry in the Journal of Ferdinand Magellan’s chronicler Antonio Pigafetta narrates an instance when Magellan asked, thru an interpreter, the Bisayan chieftains Raja Siago and Datu Kolambo “whether they were moros or heathens, or what their religions were”. It was Datu Kolambo who answered that “they were not moros but that they worship the sky god they called Abba”.

(Reference: Pages 69, 72, 73, 125 of THE BISAYAN.)