The Bible’s teaching about the two natures of Jesus Christ is the consistent understanding of Christians throughout the ages. To support this, Johann Gerhard quotes a letter written by Pope Leo from 449 AD.
Leo, Letter ad Flavian.: “The same one who is true God is also true man. There is no falsehood in this unity when the lowliness of man and the height of God are present together. After all, Just as God is not changed by pity, so man is not consumed by dignity. … Just as the Word has not departed from the equality of the Father’s glory, so His flesh has not left the nature of our race; for the Son of God and the Son of Man are truly one and the same. He is God through ‘in the beginning was the Word’ [John 1:1]; man through ‘He was made of a woman, made under the Law’ [Gal. 4:4]. The birth of His flesh is the revelation of His human nature, the birthing of the Virgin is the proof of His divine power. The infancy of the little child is shown by the humility of the cradle; the magnitude of the Most High is declared by the voices of the angels.”
Johann Gerhard On Christ 36