Yeah, St. Paul gave me a hard time, too. Then, I realized that St. Paul was doing something that the others did not understand.
He was emphasizing the Sacraments. It is only in the Sacraments that we are saved by faith apart from works. In the Sacraments, God does all the work. We merely present ourselves and profess our faith.
Colossians 2:12 Buried with him in baptism, wherein also ye are risen with him through the faith of the operation of God, who hath raised him from the dead.
The others were emphasizing good works and living a righteous life.
This is why St. Peter said that St. Paul’s teachings were hard to understand. But he acknowledged that St. Paul was also led by the Holy Spirit.
And also why St. Paul’s and St. James’ teachings seemed to contradict. Some of St. Paul’s contradict with St. James, but only if you ignore the one’s that don’t.
Romans 2:13 (For not the hearers of the law are just before God, but the doers of the law shall be justified.
Galatians 2:16 Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.
St. Paul seems to contradict with himself. Until you put these in context of the Sacraments.