Paul says the truth of the resurrection gives us a reason to be steadfast in the gospel. The resurrection of Christ is our only hope and we have good reason to be steadfast, because it is true. Secondly, it gives us a reason to stay active in service. Our service in this world counts for eternity. We not only share the gospel but live it. Finally, it is a reason to remain confident for the future. There are eternal rewards for faithfully serving Christ.