مسیحیت ارتدکس شرقی (انگلیسی: Eastern Orthodox Christianity یا Eastern Orthodoxy) یکی از سه فرقه مسیحیت خلقیدونی در کنار کاتولیسیسم و پروتستانتیسم است.[1][2]
McAuliffe, Garrett (2008). Culturally Alert Counseling: A Comprehensive Introduction (به انگلیسی). SAGE Publishing. p. 532. ISBN 978-1-4129-1006-4. About one-third of the world's population is considered Christian and can be divided into three main branches: (1) Roman Catholicism (the largest coherent group, representing over one billion baptized members); (2) Orthodox Christianity (including Eastern Orthodoxy and Oriental Orthodoxy); and (3) Protestantism (comprising many denominations and schools of thought, including Anglicanism, Reformed, Presbyterianism, Lutheranism, Methodism, Evangelicalism, and Pentecostalism).
Mirola, William; Monahan, Susanne C. (2016). Religion Matters: What Sociology Teaches Us About Religion In Our World (به انگلیسی). Routledge. ISBN 978-1-317-34451-3. Orthodox Churches represent one of the three major branches of Christianity, along with Roman Catholicism and Protestantism.
