I think a major problem is that Paul is hard to understand and people don't take the time to study his Scriptures.Ummm why are so many people against Paul's Teaching
Another is that Christianity has many enemies. Paul is just one more tool to try to discredit Christianity.
I admit that I am weak on Paul, but console myself that I am in good company. Scholars have argued endlessly about what Paul said and what he meant by what he said. It is a shame that we don't have the letters or the testimony of those he was addressing in order to understand some of his points in his letters.
The more I read Paul, the more I like him. As I said in the beginning, I don't find contradictions between Paul and Jesus and I also think that Paul and the other disciples were in tune with each other.
Another point that needs to be considered is that Paul's Scriptures for the most part represent the history of the early Christian Church--the issues that came up, the problems they were facing, etc. Paul helped the churches solve these issues. Matthew, Mark, Luke and John are primarily the Gospel of Jesus and did not deal with all the questions and issues that Paul and the church did after Jesus' resurrection. That wasn't their emphasis.
I am sort of brainstorming here and I've received some good input.