Sixtus III

Pope Sixtus III (also rendered Xystus III) was Bishop of Rome from 432 to 440. According to the Liber Pontificalis he was a Roman by birth, the son of a man named Xystus; the year of his birth is unknown. He belonged to the clergy of Rome in the early fifth century and, while still a priest, corresponded with Augustine of Hippo. In the course of the Pelagian controversy he was at one time regarded with suspicion as a possible sympathizer of Pelagius, but he subsequently stood with the opponents of Pelagianism. Augustine’s letters treat him as a figure of standing in the Roman church well before his election as pope.

Sixtus was chosen bishop of Rome on 31 July 432, succeeding Celestine I, shortly after the Council of Ephesus (431) had condemned Nestorius and upheld the title Theotokos for Mary. His pontificate was devoted in large part to securing the reception of that council in the West and to healing the rift it had opened between Cyril of Alexandria and John of Antioch. He exchanged letters with the Eastern patriarchs, urged reconciliation, and sought to preserve the communion of the churches. He also continued Rome’s resistance to Pelagian teaching and maintained papal claims over the churches of Eastern Illyricum, confirming the bishop of Thessalonica as papal vicar in that region in the face of Constantinopolitan pressure.

The most visible monuments of his reign are the churches he rebuilt or adorned in Rome. He reconstructed the old Liberian Basilica on the Esquiline and dedicated it to the Virgin Mary as Santa Maria Maggiore, furnishing it with a cycle of mosaics that illustrate Old Testament prefigurations of Christ and, on the triumphal arch, scenes of the infancy of Jesus that underline Mary’s role as Mother of God. He restored the basilica of San Pietro in Vincoli, associated with the chains of the Apostle Peter, and carried out decorative work at the Lateran baptistery, where contemporary inscriptions record his patronage. These projects expressed both the theological settlement of Ephesus and the prestige of the Roman see in the decades before the collapse of imperial authority in the West.

Sixtus III died in Rome on 18 August 440 and was succeeded by Leo I. He was buried at the Basilica of Saint Lawrence outside the Walls (San Lorenzo fuori le Mura). He has been venerated as a saint since antiquity; his traditional feast day in the Latin church is 28 March. Beyond the Liber Pontificalis, a small body of letters, and the buildings and inscriptions connected with his name, little is recorded of his personal life. No reliable evidence survives concerning a wife or children, and he is not associated with a later religious order.