11“I, only I, am the LORD, And there is no savior besides Me.
The OT especially has a strong emphasis on there being only one God, Yahweh, and there are only a few scattered and cryptic references to God even having a Son. Trinitarian doctrine tries to solve this problem at least by stating that God is one Being, but represented by three Persons. Non-trinitarians challenge this saying that God and the Son are distinct beings. They would say that Jesus is subordinate to the Father and yet this passage seems to be saying that there is no Savior apart from the Father.
The Word of God is manifested plainly in the New Testament, where Jesus seems to be distinct from the Father. But what do non-trinitarians do hermeneutically with passages in the OT like this one that seem to deny the separate existence of the Word? Why would Yahweh say there is no other Savior, whether person or being, knowing that he would be sending his Son to be the Savior of the world? Anyone should feel free to answer the question regardless of their beliefs about the trinity. Here is the verse in its immediate context.
10“You are My witnesses,” declares the LORD, “And My servant whom I have chosen, So that you may know and believe Me And understand that I am He. Before Me there was no God formed, And there will be none after Me. 11“I, even I, am the LORD, And there is no savior besides Me. 12“It is I who have declared and saved and proclaimed, And there was no strange god among you; So you are My witnesses,” declares the LORD, “And I am God. 13“Even from eternity I am He, And there is none who can deliver out of My hand; I act and who can reverse it?”