1 - Are you positive! When Paul went up to Jerusalem, he tarried idly to check things around, listened to the message of the gospel preached by the Apostles of Jesus and got terribly disappointed as he arrived to the conclusion that they were preaching a different gospel about a different Jesus. Hence, he considered them as false apostles; deceitful workers, transforming themselves into the apostles of Christ. (II Cor. 11:4-6, 13) This already says upfront that more than a gospel was being preached around; the gospel of Paul and that of the Apostles of Jesus. Then, in a letter to his disciple Timothy in II Tim. 2:8, he revealed the secret that Jesus was the Messiah and that he had resurrected was according to his gospel. It means that there was another gospel being preached, in whose agenda, Jesus was not spoken of as being the Messiah or that he had resurrected. So, what are you taking about!
2 - Perhaps, his gospel because, according to Isa. 1:18,19 the only way to set things right with God so that our sins from scarlet red become as white as snow, the only way is repentance and return to the obedience of God's Law.
3 - And you say, "if you try to be saved by keeping the Law, you will be condemned to hell." Let's make a deal. While I try to live by keeping the Law, you try to live by breaking it and let's see who will be saved. Do you have any doubt? I don't. I am quite certain of whoof the both of us will end in hell.