“…the New Testament everywhere presents [Jesus] who was both God and man. And it is interesting to observe how unsuccessful have been all the efforts to reject one part of this witness and retain the rest. The Apollinarians rejected the full humanity of the Lord, but in doing so they obtained a Person who was very different from the Jesus of the New Testament. The Jesus of the New Testament was clearly, in the full sense, a man. Other seem to have supposed that the divine and the human were so blended in Jesus that there was produced a nature neither purely divine nor purely human, but a tertium quid. But nothing could be more remote from the New Testament teaching than that. According to the New Testament the divine and human natures were clearly; the divine nature was pure divinity, and the human nature was pure humanity; Jesus was God and man in two distinct natures. The Nestorians, on the other hand, so emphasized the distinctness of divine and human in Jesus as to suppose that there were in Jesus two separate persons. But such a Gnosticizing view is plainly contrary to the record; the New Testament plainly teaches the unity of the Person of our Lord.
“By elimination of these errors the Church arrived at the New Testament doctrine of two natures in one Person; the Jesus of the New Testament is ‘God and man, in two distinct natures, and one Person forever.’ That doctrine is sometimes regarded as speculative. But nothing could be further from the fact. Whether the doctrine of the two natures is true or false, it was certainly produced not by speculation, but by an attempt to summarize, succinctly and exactly, the Scriptural teaching.”
(J. Gresham Machen, “Christ,” Christianity and Liberalism, pp 97-98, 1923)