Wherefore be of good cheer (dio euthumeite). God had spoken. That was enough. This old verb from euthumos in the N.T. only here, Act 27:25; Jam 5:13. See the adjective Act 27:36.
For I believe God (pisteuō gar tōi theōi). This is Paul’s reason for his own good cheer and for his exhortation to confidence in spite of circumstances so untoward. Paul had doubtless prayed for his own life and for the lives of all. He was sure that he was to bear his witness in Rome.