Since
@ATP mentioned the Nicene Creed, here's the full text:
I believe in one God,
the Father almighty,
maker of heaven and earth,
of all things visible and invisible.
I believe in one Lord Jesus Christ,
the Only Begotten Son of God,
born of the Father before all ages.
God from God, Light from Light,
true God from true God,
begotten, not made, consubstantial with the Father;
through him all things were made.
For us men and for our salvation
he came down from heaven,
and by the Holy Spirit was incarnate of the Virgin Mary,
and became man.
For our sake he was crucified under Pontius Pilate,
he suffered death and was buried,
and rose again on the third day
in accordance with the Scriptures.
He ascended into heaven
and is seated at the right hand of the Father.
He will come again in glory
to judge the living and the dead
and his kingdom will have no end.
I believe in the Holy Spirit, the Lord, the giver of life,
who proceeds from the Father and the Son,
who with the Father and the Son is adored and glorified,
who has spoken through the prophets.
I believe in one, holy, catholic and apostolic Church.
I confess one Baptism for the forgiveness of sins
and I look forward to the resurrection of the dead
and the life of the world to come. Amen
Notice something? No mention of Yahweh as a person of the trinity. Jesus is called "Lord", "Κύριον", the word used for Yahweh in Greek. And the Holy Spirit is also called the Lord, "Κύριον". But no mention of "Yahweh" alone as a person of the Trinity.
Notice one other thing though - it says the Holy Spirit "has spoken through the Prophets". Who are the Prophets? Moses, Jeremiah, Isaiah, etc. The authors of the Old Testament Scriptures.
@ATP , your own tradition says God has spoken through the Prophets. You are denying your own tradition when you say things like the Old Testament "was written by people who could make mistakes and didn't understand facts". The Old Testament is what God spoke through the Prophets. I don't think it's a good idea to dismiss or ignore what God has spoken, do you?
God spoke through Isaiah to say that he is one God, Yahweh, and that there is no one beside him. The Nicene Creed affirms there is one God. The one God the Nicene Creed describes is the one God who spoke through Isaiah, Yahweh. He
is the Trinity. God is the Father, God is the Lord Jesus Christ, and God is the Holy Spirit. Yahweh is the Father, Yahweh is the Lord Jesus Christ, and Yahweh is the Holy Spirit.
That is the whole dogma that the Nicene Creed affirms. So for you to suggest that saying Jesus is Yahweh is somehow "new heresy" is just...you really do not know what you are talking about.
You are the heretic to deny that, even by the tradition of the Roman Catholic church.
