God had said that Paul would preach before kings and that he would reach Rome. God's chosen path for Paul to fulfill these promises was in chains as a prisoner for his faith. Paul's trust in God and his continuing to preach the gospel in the face of false accusations, unjust sentencing, and possible torture and death is an example of confidence in the power of the gospel to save.
Because God has fulfilled His greatest promise in providing salvation through Jesus, we live on mission without wavering, even when our work seems futile and the furture unsure.