Paul is not the only Apostle.
Apostolic Authority comes from the Apostles acting together and agreeing, not one of them alone.
***
...you are claiming that the Apostles taught literally the exact opposite from each other?
Is that what you’re claiming?
...you are claiming that the Apostles taught literally the exact opposite from each other?
Is that what youre claiming?
_______________________________________________
I made this in my last point, but I’ll say it again. The Epistle of James was a rebuke of the One-and-Done Faith position that could be attributed to Paul. Here’s what Martin Luther (a famous lover of the Apostle Paul) said about the Book of James:
Therefore St James epistle is really an epistle of straw, compared to these others, for it has nothing of the nature of the Gospel about it.