Why are Paul's writings in the Bible?

[GrandizerII]

I had a look at that link. Some of the thngs I naturally agree with (because the thought has crossed my mind several times since leaving the faith that Paul was quite a BSer, though Tabor trusts Paul more than I do apparently, and because Acts is all one big book of legends about the Apostles):

Acts’s claim that Paul grew up in Jerusalem and was a personal student of the famous rabbi Gamaliel is also highly suspect.

...

Whether Paul even lived in Jerusalem before his visionary encounter with Christ could be questioned. In Acts it is a given, but Paul never indicates in any of his letters that Jerusalem was his home as a young man. He does mention twice a connection with Damascus, the capital of the Roman province of Syria (2 Corinthians 11:32; Galatians 1:17). Whether he was in Damacus, which is 150 miles northwest of Jerusalem, in pursuit of Jesus’ followers, or for other reasons, we have no sure way of knowing. The account in Acts of Paul’s conversion, repeated three times, that has Paul sent as an authorized delegate of the High Priest in Jerusalem to arrest Christians in Damascus, has so colored our assumptions about Paul that it is hard to focus on what we find in his letters.
Paul connection to Jerusalem, or the lack thereof, has much to do with the oft-discussed question of whether Paul would have ever seen or heard Jesus, or could he have been a witness to Jesus’ crucifixion in A.D. 30. Since he never mentions seeing Jesus in any of his letters, and one would expect that had he been an eyewitness to the events of that Passover week he surely would have drawn upon such a vivid experience, this argues against the idea that he was a Jerusalem resident at that time.

Likewise, Paul’s high placed connections to the Jewish priestly class in Jerusalem we can neither confirm nor deny. All he tells us is that he zealously persecuted the church of God and tried to destroy it (Galatians 1:12). Some translations have used the English word “violently,” but this is misleading and serves to reinforce the account in Acts that Paul was delivering people over to execution. The Greek word Paul uses (huperbole) means “excessively” or zealously. We take Paul’s word that he identified himself as a Pharisee, but there is nothing in his letters to indicate the kind of prominent connections that the author of Acts gives him.

This is why any argument along the line of "well, why wasn't Paul mentioned in any secular/Judaic source at the time" is moot since these are often based on the legends/exaggerated details about Paul rather than what anything Paul may have actually said that sounded genuine.

Personally, I think whatever Paul meant to say exactly regarding persecuting Christians in his past life, he was exaggerating what he did, to make himself sound like he was the worst of the worst before he became the best of the best. So maybe there is a grain of truth to him having been mean to Christians, but I think this got overblown through his exaggerations and through the beliefs of later Christians

As for Paul not being born in Tarsus, maybe. I don't know if we should take Jerome as authority given he came much later. And even if he was using an earlier source, what was it exactly? I don't personally have enough details related to that to put any stock in this tradition.