Sorry - to most of us Christians, quoting from Doctrine & Covenants is proof of nothing, just a book made up in the 19th century.
One could also say some who don’t believe (Atheist) or that is of the Jewish faith in their opinion the New Testamnet is a not a fact.
It’s OK. You don’t have to believe anything you don’t want to.
But my first question is always: Have you read it?
My second question is: Did you pray before you read it?
If the answer to either question is “No,” then it’s still OK if you don’t believe. “Free agency,” and all that!
You mean made up out of whole cloth like the Trinity business? Or do you mean fabricated like that Calvinist stuff?