Flavius Valerius Aurelius Constantinus (27 February ca. 272 – 22 May 337), commonly known as Constantine I, Constantine the Great, or Saint Constantine (among Eastern Orthodox and Byzantine Catholic Christians), was Roman Emperor from 306, and the undisputed holder of that office from 324 to his death. Best known for being the first Christian Roman Emperor, Constantine reversed the persecutions of his predecessor, Diocletian, and issued (with his co-emperor Licinius) the Edict of Milan in 313, which proclaimed religious toleration throughout the empire. The Byzantine liturgical calendar, observed by the Eastern Orthodox Church and Eastern Catholic Churches of Byzantine rite, lists both Constantine and his mother Helena as saints. Although he is not included in the Latin Church's list of saints, which does recognize several other Constantines as saints, he is revered under the title "The Great" for his contributions to Christianity.