Paul considered himself Christs ambassador. What is an ambassador? He is an authorized representative of a sovereign. He speaks not in his own name but on behalf of the ruler whose deputy he is, and his whole duty and responsibility is to interpret that rulers mind faithfully to those to whom he is sent.
Paul used this “ambassador” image twice -- both in connection with his evangelistic work. Pray for me, he wrote from prison, “that utterance may be given me in opening my mouth boldly to proclaim the mystery of the gospel, for which I am an ambassador in chains; that I may declare it boldly, as I ought to speak” (Eph. 6:18-20). He wrote also that God “gave us the ministry of reconciliation So we are ambassadors for Christ, God making his appeal through us. We beseech you on behalf of Christ, be reconciled to God” (2 Cor. 5:18-20).
Paul called himself an ambassador because he knew that when he proclaimed the gospel facts and promises and urged sinners to receive the reconciliation effected at Calvary, he was declaring Christs message to the world. The figure of ambassadorship highlights the authority Paul had, as representing his Lord, as long as he remained faithful to the terms of his commission and said neither less nor more than he had been given to say.