Chalcedonian Christianity is the branch of Christianity that accepts and upholds theological and ecclesiological resolutions of the Council of Chalcedon, the Fourth Ecumenical Council, held in 451. Chalcedonian Christianity accepts the Christological Definition of Chalcedon, a Christian doctrine concerning the union of two natures (divine and human) in one hypostasis of Jesus Christ, who is thus acknowledged as a single person (prosopon). Chalcedonian Christianity also accepts the Chalcedonian confirmation of the Niceno-Constantinopolitan Creed, thus acknowledging the commitment of Chalcedonism to Nicene Christianity.