Isaiah 45:6
That they may know from the rising of the sun, and from the west, that there is none beside me. I am the LORD, and there is none else.
Primary
What this passage establishes
From east to west, people are to know that there is no God beside the LORD.
Why it matters in the argument
This establishes the controlling biblical confession: every later passage about Father, Son, and Holy Ghost must be read without multiplying the one God.
Apostolic connection
Apostolic teaching begins with the Bible’s own insistence that God is one indivisible divine being, then reads the incarnation as that one God revealed in Christ.
Common misunderstanding
Counting titles, manifestations, or relational language does not overturn the Bible’s explicit statements that God is one and alone.
How to use it in conversation
Start here before discussing difficult relational texts. Establish what Scripture says plainly about how many are God.