2 Corinthians 5:20

We are ambassadors therefore on behalf of Christ

(υπερ Χριστου ουν πρεσβευομεν). Old word from πρεσβυς, an old man, first to be an old man, then to be an ambassador (here and Ephesians 6:20 with εν αλυση in a chain added), common in both senses in the Greek. "The proper term in the Greek East for the Emperor's Legate" (Deissmann, Light from the Ancient East, p. 374), in inscriptions and papyri. So Paul has a natural pride in using this dignified term for himself and all ministers. The ambassador has to be persona grata with both countries (the one that he represents and the one to which he goes). Paul was Christ's Legate to act in his behalf and in his stead.As though God were intreating by us

(ως του θεου παρακαλουντος δι' ημων). Genitive absolute with ως used with the participle as often to give the reason (apparent or real). Here God speaks through Christ's Legate.Be ye reconciled to God

(καταλλαγητε τω θεω). Second aorist passive imperative of καταλλασσω and used with the dative case. "Get reconciled to God," and do it now. This is the ambassador's message as he bears it to men from God.