Why did Paul suffer for the gospel?

Les explains that Paul was appointed a preacher, an apostle, and a teacher of the Gentiles, and for that cause he suffered these things. His chief opposition was the Jew—both believing Jews and those still steeped in Judaism—but it was not the Jew alone; it was also a satanic power from every direction. Satan did not want the gospel going to the Gentile world. It had gone to Israel throughout the Old Testament, but now going to the masses of Gentiles was the last thing Satan wanted. Paul therefore suffered for these things, yet was not ashamed, for he knew whom he had believed. In spite of all his difficulties, sickness, sorrow, and suffering, he never once doubted the God he served.