Born in Tarsus, Cilicia (modern-day Turkey) in about the year 602, Theodore was educated in Athens and Constantinople, accumulating vast knowledge in theology, law, medicine, and philosophy. After fleeing the Arab conquests, he moved to Rome. In 668 AD, at the advanced age of 66, Pope Vitalian appointed him Archbishop of Canterbury to unify the fractured English Church.
Arriving in Britain in 669 AD alongside Saint Adrian, Theodore embarked on an energetic reform campaign. He filled long-vacant episcopal sees, subdivided unwieldy dioceses, and established sound church governance. In 672 AD, he convened the Synod of Hertford, the first national council of the English Church, establishing unified canon law and ending lingering Celtic–Roman liturgical divisions.
Together with the Abbot St. Adrian, St. Theodore founded a legendary school at Canterbury, making it a world-class center of learning where Greek, Latin, astronomy, and theology were taught. By the time of St. Theodore’s death in 690 AD, Saint Bede famously noted that Theodore was the first archbishop whom the entirety of the English Church obeyed, laying the administrative groundwork for both a unified church and, ultimately, a unified nation.
O GOD, whose Bishop Theodore was called to England to set the Church on a firm foundation: by his prayers, build us always anew on the rock that is Christ; and keep thy household faithful to the call we have received; through Jesus Christ thy Son our Lord, who liveth and reigneth with thee, in the unity of the Holy Spirit, ever one God, world without end. Amen.