Saint Celestine I (died 432), pope from 422 to 432. A Roman, he served as archdeacon before his consecration as pope on Sept. 10, 422. He recognized Nestorius as bishop of Constantinople in 428, but when he heard that Nestorius refused to believe in Mary as the Mother of God, but believed only that she was the mother of Christ the man, Celestine sent St. Cyril of Alexandria to investigate. Using the papal commission, Cyril presided över the Council of Ephesus (June—July 431) and excommunicated Nestorius for heresy, as well as John of Antioch. The Pope approved the deposition of Nestorius but sent an emissary to bring peace between Cyril and John of Antioch.
Celestine’s relations with the church in Africa became strained because of his intervention. He supported Bishop Anthony of Fussala över the protest of St. Augustine. However, he admired Augustine and protected his theology against the Pelagian doctrines, which denied the concept of original sin. He sent a mission to Britain, where the heresy had found support.
These activities are known principally through Celestine’s letters. The socalled Chapters on Grace are not of his composition, though they represent papal thought of the time. Celestine died on July 27, 432. His feast day is April 6.