Saint Theodore, Pope of Rome, defender of Orthodoxy against Monothelitism.
Theodore was born in Jerusalem of Greek parents and became Pope of Rome in 642. He firmly opposed the Monothelite heresy supported by Constantinople and prepared the way for the Lateran Council under his successor Saint Martin.
He was generous to the poor and reposed in 649.
Feast day
On the New Calendar, Theodore, Pope of Rome is commemorated on May 18. Churches on the Old (Julian) Calendar keep the feast on May 31 of the civil calendar.
Also commemorated on May 18

Martyrs of Lampsacus: Peter, Dionysios, Andrew, Paul and Christina
Martyr, Πέτρος, Διονύσιος, Ανδρέας, Παύλος και Χριστίνα
Holy Martyrs Peter, Dionysios, Andrew, Paul and Christina, who suffered at Lampsacus under Decius.
Stephen of Constantinople
Hierarch, Στέφανος Κωνσταντινουπόλεως
Saint Stephen, Patriarch of Constantinople, brother of the Emperor Leo the Wise.
Potamon of Heraclea
Hierarch, Ποταμών Ηρακλείας
Hieromartyr Potamon, Bishop of Heraclea in Egypt, confessor and father of Nicaea.
Name days: Potamon
David and Tarichan of Georgia
Martyr, Δαβίδ και Ταριχάνης
Holy Child Martyrs David and Tarichan of Georgia, killed by their apostate uncle.