Offa was a Christian king, but came into conflict with the Church, and in particular with Jaenberht, the Archbishop of Canterbury. Offa managed to persuade Pope Adrian I to divide the archdiocese of Canterbury in two, creating a new archdiocese of Lichfield. This reduction in the power of Canterbury may have been motivated by Offa's desire to have an archbishop consecrate his son Ecgfrith of Mercia as king, since it is possible Jaenberht refused to perform the ceremony, which took place in 787. Offa had a dispute with the Bishop of Worcester which was settled in the Council of Brentford in 781.
Many surviving coins from Offa's reign carry elegant depictions of him and the artistic quality of these images exceeds that of the contemporary Frankish coinage. Some of his coins carry images of his wife, Cynethryth—the only Anglo-Saxon queen ever depicted on a coin. Only three gold coins of Offa's have survived: one is a copy of an Abbasid dinar of 774, and carries Arabic text on one side of the coin, with "Offa Rex" on the other side. The gold coins are of uncertain use but may have been struck to be used as alms or for gifts to Rome.