1) During the Yuan dynasty mongols makes efforts for concentrating oriental christians, nestorians etc. in the coastal China, reasons unimportant (let's say they believed that they are more skilled in trade and finances, aka. Jews of Asia)
2) Red Turban Rebellion starts, Yuan starts to fall, and the said christians simply transport their entire communities to the Phillipines, to escape the chaos.
3) By late 16 cent when Spain enters the area the culture of the islands is already assimilated in the unique, ethiopian like version of orthodox christianity, and cordial relations with trade benefits start. Spain makes no effort of conquest.
4) Vitus Bering, danish explorer in the employment of Peter the Great that discovered Alaska has heard about the stated christian society, and goes down to establish relations.
5) Thus came 19 cent, Russia got Vladivostok and Japan starts to get frisky in the region so who will be better protector of the island nation than the Rodina.