Jerusalem still has an Orthodox Patriarch.
en.wikipedia.org/wiki/Greek_Orthodox_Patriarch_of_Jerusalem
As for the claim that Paul “created Christianity” I would remind these individuals that their are 4 Gospels that describe the ministry and teachings of Jesus, and they are free to learn and study those to point out where Paul errs in his theological beliefs when discussing Christ.
Paul is the whipping boy for almost anything and everything people find wrong with Christianity. He is an easy target since his claim of Apostolic Authority came from meeting the resurrected Christ, and because he was a bulldog of orthodoxy, frequently rebuking the Churches of the Gentile world for falling away from the true Gospel.
What is humorous is that people were saying the same things about Paul when he lived too.

His relationships with many of the other Apostles were frequently strained and punctuated by disagreement and maybe lost friendships, see Barnabus.
To me, Paul’s witness is some of the strongest proof that Christianity is what it says it is. Saul was a Pharisee on the fast track to importance, he was a Roman citizen, all one must do is read his Epistles to see the sharpness and expansiveness of his mind and soul.
He had no reason to subject himself to a live of imprisonment, torture, living hand to mouth, being rejected and run out of many towns, being called a fool by Jews and Gentile alike, and ultimately suffering martyrdom, unless he believed what he was teaching was the Truth that would set the world free. There was nothing of material gain for him in his missionary work, he did it for Christ, and for us.