Since there are scriptures that could take this issue either way we must find the bottom line, then we can build our understanding upon it. I believe the root of Trinitarian error is their interpretation of the word ONE. If one means “only one”as applied to God the Catholic, Orthodox,and their offspring Protestant churches are mixed up in their teaching.
How do we determine the meaning?
Hear O Israel: The Lord our God is ONE LORD:And thou shalt love the Lord thy God with all thine heart,and with all thy soul,and with all thy might. Deut.6:4-5
The Hebrew word for ONE is “echad”. It can be used to mean ONLY or UNITED. Those who say echad never means a solitary ONE have not taken the time to look it up in the Strongs no. 259.
Reading verses where this word means one and only would TAKE ALL DAY to accomplish. If you want to know if this is true just try it. Now if God says he is ONE and there is NONE ELSE he certainly means one in the one and only sense.
If he were two or three he might have said to us,”I am God along with several others”.
Nothing in the context of Duet.6:4-5 points to the word ONE meaning plurality in unity. Israel never took it that way. They believed they served a God who was THE ONLY GOD. When God introduced himself to Moses it was on this wise:
And God said unto Moses I AM THAT I AM: Ex.3:14
Notice he did not say WE ARE WHAT WE ARE. He was revealing himself as THE ONLY GOD.
Oneness doctrine starts from the position that when applied to God the word ONE actually means ONE. HE not THEY. HIM not THEM. I build what I believe about Oneness with this understanding. The Trinitarians start with a FALSE PREMISE that ONE GOD DOESNT REALLY MEAN ONE GOD. Right at that point they make it impossible to understand the Godhead.
The apostles were Jewish one God people. They never heard any preaching about their
God having ONE OR TWO OTHER CO EQUAL,CO ETERNAL,OTHER SEPERATE BUT ONE IN UNITY TEACHING. They were more used to the one God preaching of prophets like Isaiah.
Look unto me and be ye saved, all the ends of the earth: for I am God and there IS NONE ELSE. Isaiah 45:22
So if the Apostles believed Yeshua was indeed God, he was the ONLY GOD for they believed there was none else but HE.
Oneness is simply a word describing two foundational truths.
1. God is THE ONLY GOD
2. Yeshua is God.
All teaching on the Godhead must start FROM THIS REFERENCE POINT.