The Eastern Orthodox Church is fully Chalcedonian in its Christology, accepting all seven Ecumenical Councils. The Council of Chalcedon (451) defined that Jesus Christ is one divine Person (hypostasis) existing in two complete and unconfused natures—divine and human—'without mixture, confusion, separation, or division.' The Third Council of Constantinople (681) further defined that Christ has two wills (divine and human), perfectly aligned, against the Monothelite heresy. This distinguishes the Eastern Orthodox from the Oriental Orthodox (who accept only three Councils).

Mary is venerated as Theotokos (God-bearer), a title essential to Orthodox Christology: because Christ is one divine Person, his mother is truly the Mother of God. Orthodox iconography, shaped by the decisions of Nicaea II (787), presents Christ as fully human (and therefore depictable) and fully divine (and therefore worthy of worship). The icon is a theological statement about the reality of the Incarnation. Orthodox Christology is expressed most fully in the Divine Liturgy and the liturgical hymnography of the Triodion, Pentecostarion, and Menaion.