Sacred tradition, also called holy tradition or apostolic tradition, is a theological term used in Christian theology. According to this theological position, sacred Tradition and Scripture form one deposit, so sacred Tradition is a foundation of the doctrinal and spiritual authority of Christianity and of the Bible. Thus, the Bible must be interpreted within the context of sacred Tradition and within the community of the denomination. The denominations that ascribe to this position are the Catholic, Eastern Orthodox, and Oriental Orthodox churches, and the Assyrian churches.

Eastern Orthodoxy, otherwise known as Eastern Orthodox Christianity or Byzantine Christianity, is one of the three main branches of Chalcedonian Christianity, alongside Roman Catholicism and Protestantism. Like the Pentarchy of the first millennium, the mainstream Eastern Orthodox Church is organised into autocephalous churches independent from each other. In the 21st century, the number of mainstream autocephalous churches is seventeen; there also exist autocephalous churches unrecognized by those mainstream ones. Autocephalous churches choose their own primate. Autocephalous churches can have jurisdiction (authority) over other churches, some of which have the status of "autonomous" which means they have more autonomy than simple eparchies.