The Chalcedonian Definition
Following, then, the holy fathers, we all unanimously teach that our Lord Jesus Christ is to us one and the same Son, the self-same perfect in Godhead, the self-same perfect in manhood; truly God and truly man; the self-same of a rational soul and body; co-essential with the Father according to the Godhead, the self-same co-essential with us according to the manhood; like us in all things, sin apart; before the ages begotten of the Father as to the Godhead, but in the last days, the self-same, for us and for our salvation (born) of Mary the Virgin Theotokos as to the manhood; one and the same Christ, Son, Lord, only-begotten; acknowledged in two natures unconfusedly, unchangeably, indivisibly, inseparably; the difference of the natures being in no way removed because of the union, but rather the properties of each nature being preserved, and (both) concurring into one person and one hypostasis; not as though He were parted or divided into two persons, but one and the self-same Son and only-begotten God, Word, Lord, Jesus Christ; even as from the beginning the prophets have taught concerning Him, and as the Lord Jesus Christ Himself hath taught us, and as the symbol of the fathers hath handed down to us.
Regarding the Chalcedonian Definition
Recognized at an ecumenical council in 451 AD, the full Chalcedonian Definition is quite long, and includes two versions of the Nicene Creed (325 & 381 AD). The above abbreviated portion of the Definition is the concluding paragraph of its longer form, carefully articulating biblical truth about Christ. There are several English translations of the Definition which vary slightly in their translation of the Greek text – the above translation is courtesy of Ligonier Ministries.