Why did pope pius v excommunicate queen elizabeth i in 1570? the pope deemed her a heretic because she declared the church of england independent of vatican authority. the pope declared her a heretic because she sided with charles v to form the schmalkaldic league. the pope declared her a heretic because she invaded france and spain, allies of the catholic church. the pope declared her a heretic because she refused to send english troops to aid rome when it was sacked by spanish marauders.