December 31 (Eastern Orthodox liturgics)

Dec. 30 - Eastern Orthodox liturgical calendar - Jan. 1

All fixed commemorations below are observed on January 13 by Orthodox Churches on the Old Calendar.

For December 31st, Orthodox Churches on the Old Calendar commemorate the Saints listed on December 18.

Venerable Melania the Younger, Nun of Rome
(Menologion of Basil II, 10th century)

Pope St. Sylvester I and Emperor Constantine.

Adoration of the Cross by Pope St. Sylvester I, Empress Helena and Emperor Constantine.

Saint Theophylactus of Ohrid.

St. Peter (Mogila) of Kiev, Defender of the Orthodox faithful against subjugation to the Roman Papacy ('Unia').

New Hiero-Confessor , Metropolitan of Zagreb (1945).

Greek Sources

Russian Sources

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Wikipedia