Is Trinitarian language an imposition or intrinsic to Christian theology?
Suppose one heard a lesson that went something like this: "Jesus, the carpenter from the town of Nazareth, went into town to fetch himself a pail of water and buy a loaf of bread to take back home to share with his mother, and this same Jesus is the Christ the Son of the living God." Theologians like Nestorius, the archbishop of Constantinople, would agree with this statement saying it was true. However, if I took that same statement with some minor adjustments saying instead: "There is God going into town to fetch himself a pail of water and buy a loaf of bread to take back home to share with his mother," Nestorius would reject this statement claiming that actions such as fetching water, buying bread, eating, and drinking, are "idiomata" for humans, but not for the divine. Likewise, to say something like "Jesus the carpenter was crucified by the Jews," would be fine by Nestorius, but to say that, "God was crucified by the Jews," would be to associate "idiomata," or inherent order of nature, of humans to the divine.
The motivation of viewing Christ as two distinct persons developed against the idea that God suffered and died on the cross, for it was axiomatic to most patristic writers that God was capable of suffering in the same ways human beings suffer. For those who followed after Nestorius' teachings, they believed Jesus the perfect human suffered and died, not the divine second person of the Trinity. This can be thought as if a man went into a tent that was not his and put the clothes of another man on himself. The man is fully himself, while also be disguised or masked as another, being also fully him.
Theological issues such as the one that is depicted above found rise in the elaboration of the Trinity. If Godhead was truly united, then anything that happened to one must also be true of the others. The traditional stance of those who supported the "two natures" of Jesus can be found in the creedal statement from the Council of Nicaea:
We believe in one God, the Father Almighty, Maker of all things visible and invisible. And in one Lord Jesus Christ, the Son of God; the only-begotten, begotten of the Father, that is, of the substance of the Father; God of God, Light of Light, true God of true God; begotten, not made; of the same substance as the Father; through whom (1) all things were made, both those in heaven and those on earth; who for us men and for our salvation came down, took flesh, and was made man, suffered, and rose up on the third day, ascended into heaven, and will come to judge the living and the dead. And in the Holy Spirit. (Jurgens, 281)
This stance was difficult for many to support. Theologians like Tertullian could not stand for such a view, crying out, "Let this blasphemy be silent, let it be silent. Let it be enough to say that Christ the Son died…" It was difficult enough to ascribe death to the Son of the living God, but to claim suffering and death upon the Godhead was pure blasphemy. As pointed out by Pelikan, this accusation not only prescribed suffering and death upon the Godhead, but instead of the Father sending the Son to the cross, it reflects that the Father had sent himself there (Pelikan, 180). It simply could not be accepted that the Father shared in the suffering of the Son.
The relationship between the entities of the Trinity were just beginning to come under stronger examination. As shown above the relation of the one to the three bled into an evens larger discussion of the relation between the Son and the Father. Finely stated by Pelikan, "In one sense, the dogma of the Trinity was the end result of theology, for it brought together many of the themes of the preceding development. But in another sense, it was the starting point" (Pelikan, 223-224).