The term "Chalcedonian" refers to the doctrines established by the Council of Chalcedon, which took place in 451 AD. This ecumenical council was significant in defining the nature of Jesus Christ, affirming that He is both fully divine and fully human, united in one person. This doctrine is known as the "Chalcedonian Definition." Chalcedonian Christianity emphasizes the importance of this dual nature of Christ, which has influenced many branches of Christianity, particularly Eastern Orthodoxy and Roman Catholicism. The council's decisions aimed to address various theological disputes and promote unity within the early Christian church.