You have to remember I'm one of the most knowledgeable guys in the world on the subject of the New Testament. I can't even read most of the Epistles because I have it memorized and therefore can only skim it at best. So I know that God would clearly teach the trinity so simple that a child could understand it if there was such a thing. It would be more like...
Verily, verily I say unto you that I am Jesus and I'm also God.
The Epistles would have writings like...
Yay, I Paul do testify that Jesus who is God came down from heaven to be a man for us. And we do know and testify that this same Jesus who you crucified is God. And so let us bow our knee to the one and only true God-Man Jesus Christ.
And yet there's nothing like that anywhere. Not in the Old or New Testament. Not even one complete verse like that.