Ἑπόμενοι τοίνυν τοῖς ἁγίοις πατράσιν ἕνα καὶ τὸν αὐτὸν ὁμολογεῖν υἱὸν τὸν κύριον ἡμῶν Ἰησοῦν Χριστὸν συμφώνως ἅπαντες ἐκδιδάσκομεν, τέλειον τὸν αὐτὸν ἐν θεότητι καὶ τέλειον τὸν αὐτὸν ἐν ἀνθρωπότητι, θεὸν ἀληθῶς καὶ ἄνθρωπον ἀληθῶς τὸν αὐτὸν, ἐκ ψυχῆς λογικῆς καὶ σώματος, ὁμοούσιον 66 τῷ πατρὶ κατὰ τὴν θεότητα, καὶ ὁμοούσιον τὸν αὐτὸν ἡμῖν κατὰ τὴν ἀνθρωπότητα, κατὰ πάντα ὅμοιον ἡμῖν χωρὶς ἁμαρτίας· πρὸ αἰώνων μὲν ἐκ τοῦ πατρὸς γεννηθέντα κατὰ τὴν θεότητα, ἐπ᾽ ἐσχάτων δὲ τῶν ἡμερῶν τὸν αὐτὸν δἰ ἡμᾶς καὶ διὰ τὴν ἡμετέραν σωτηρίαν ἐκ Μαρίας τῆς παρθένου τῆς θεοτόκου κατὰ τὴν ἀνθρωπότητα ,68 ἕνα καὶ τὸν αὐτὸν Χριστόν, υἱόν, κύριον, μονογενῆ, ἐκ δύο φύσεων [ἐν δύο φύσεσιν] , ἀσυγχύτως, ἀτρέπτως , ἀδιαιρέτως, ἀχωρίστως γνωριζόμενον· οὐδαμοῦ τῆς τῶν φύσεων διαφορᾶς ἀνῃρημένης διὰ τὴν ἕνωσιν, σωζομένης δὲ μᾶλλον τῆς ἰδιότητος ἑκατέρας φύσεως καὶ εἰς ἓν πρόσωπον καὶ μίαν ὑπὸστασιν συντρεχούσης, οὐκ εἰς δύο πρόσωπα μεριζόμενον ἢ διαιρούμενον, ἀλλ᾽ ἕνα καὶ τὸν αὐτὸν υἱὸν καὶ μονογενῆ, θεὸν λόγον, κύριον Ἰησοῦν Χριστόν· καθάπερ ἄνωθεν οἱ προφῆται περὶ αὐτοῦ καὶ αὐτὸς ἡμᾶς ὁ κύριος Ιησοῦς Χριστὸς ἐξεπαίδευσε καὶ τὸ τῶν πατέρων ἡμῖν καραδέδωκε σύμβολον.
We, then, following the holy Fathers, all with one consent, teach men to confess one and the same Son, our Lord Jesus Christ, the same perfect in Godhead and also perfect in manhood; truly God and truly man, of a reasonable [rational] soul and body; consubstantial [coessential] with the Father according to the Godhead, and consubstantial with us according to the Manhood; in all things like unto us, without sin; begotten before all ages of the Father according to the Godhead, and in these latter days, for us and for our salvation, born of the Virgin Mary, the Mother of God, according to the Manhood; one and the same Christ, Son, Lord, Only-begotten, to be acknowledged in two natures,inconfusedly, unchangeably,indivisibly, inseparably; the distinction of natures being by no means taken away by the union, but rather the property of each nature being preserved, and concurring in one Person and one Subsistence, not parted or divided into two persons, but one and the same Son, and only begotten, God the Word, the Lord Jesus Christ, as the prophets from the beginning [have declared] concerning him, and the Lord Jesus Christ himself has taught us, and the Creed of the holy Fathers has handed down to us.
The 4th Ecumenical Council was held at Chalcedon in 451. Any tdaching on the nature of Christ which departs from this has been heresy for nearly 1600 years.