Orthodoxy (from Ancient Greek ὀρθοδοξία (orthodoxía) 'righteous/correct opinion') is adherence to a purported "correct" or otherwise mainstream- or classically accepted creed, especially in religion.
Orthodoxy within Christianity refers to acceptance of the doctrines defined by various creeds and ecumenical councils in antiquity, but different Churches accept different creeds and councils. Such differences of opinion have developed for numerous reasons, including language and cultural barriers. In the Christian world, Eastern Orthodoxy and Oriental Orthodoxy are sometimes referred to simply as "the Orthodox" or "Orthodoxy".