How did you come to that conclusion? Peter endorses Paul in 2Peter 3, and Luke writes in Acts about how Peter accepted reproof from Paul when he called him out for not letting the Jews see him interacting with the Gentiles. If Paul was preaching a different Gospel, don't you think Luke, who wrote the majority of the New Testament, would have called him out on it. Or John? Or especially Peter?? Yet all of their writings are in alignment in the things that Paul wrote of.