I want you to know, brothers and sisters, that the gospel I preached is not of human origin. I did not receive it from any man, nor was I taught it; rather, I received it by revelation from Jesus Christ.
This is such a bold claim. One that makes so much sense to those who get it, and is utter nonsense to those who do not.
When looking at the gospel, especially a gospel that would be invented by such a potentially prominent Jew, the gospel that Paul preaches makes no sense. It gains him nothing, and costs him everything. So unless it is true, Paul is insane.
I don't think he was insane, so listening or reading this is more than just something to do, it is something to investigate. It is something to work out. It is something to test. And if found to be true, it is something to live out in the same manner that Paul lived it out. Anything less seems insane.