The most dangerous heresy to the Catholic Church in the first thousand years of its existence. Arianus, the Alexandrine bishop for whom to the heresy is named, believed Christ was wholly mortal, in no way divine except for the teachings he revealed. Arianus was active from the years 318-355, and his beliefs gained enormous popularity, although they were repeatedly condemned by the Church. Many of the barbarian tribes of Europe converted to Arianism, not Catholicism. By the time Clovis II became king of France, Arianism had almost completely eclipsed Catholicism.