MESIA, EVANGELIZATION OF. – The name MESIA, which appears only with the Roman conquest, did not have, throughout the history of the Empire, a constant geographical value. Very roughly, it can be said that the region so named was bounded to the south by the chain of the Haemus (Balkans), to the north by the course of the Lower Danube, to the east by the Black Sea, and to the west by the course of the Drin and the mountains that border Bosnia and Dalmatia.
The territory began to be traversed by Roman armies in the last century of the Republic, was constituted as a province by Augustus, and then reorganized anew by Tiberius after the Pannonian insurrection. Domitian subdivided it into two provinces, Moesia Superior (Serbia) and Moesia Inferior (parts of Bulgaria and Romania as far as the mouths of the Danube). Later, when Aurelian, under persistent barbarian pressure, definitively abandoned the lands north of the Danube (Dacia), he brought south of the river not only the garrisons of that province but also, as a good omen, the name, creating at the expense of Upper Moesia two new provinces: Dacia Ripensis and Dacia Mediterranea.
Christian preaching, as set forth in the Acts of the Apostles, did not reach Moesia, but since those Acts are essentially the Acts of Paul, the tradition collected by Eusebius—that the apostle Andrew carried the evangelical mission to these remote Danubian regions (Eusebius, Hist. ecc., III, 1)—cannot be entirely dismissed, even if no credence is to be given to the so-called Acts of Andrew, which are certainly apocryphal (J. Flamion, Les Actes apocryphes d'André, Louvain 1911). Moreover, it can be reasonably supposed that the ancient Christian communities of Thrace and Macedonia (Philippi, Beroea, Thessalonica) radiated into nearby Moesia.
It has even been suggested that a Julius Bassus, governor of Lower Moesia in 161 (CIL, III, 6169), may have been a Christian, since his name was found as that of a father of a Julia deposited in a Christian sarcophagus in the Catacomb of Callisto (O. Marucchi, Le catacombe romane, Rome 1933, p. 227). The first positive documents, however, are rather the Passions of certain martyrs during the persecution of Diocletian. It is known that in that persecution much effort was made to eliminate Christian infiltrations in the ranks of the army, and therefore the martyrdom of six soldiers from the Danubian garrisons (Julius, Hesychius, Nicander, Marcian, Pasicrates, Valentine) seems admissible even to H. Delchaye (v. BIBLICA). Also credible seems the report of the martyrdom at Sirmium of a priest Montanus. Less worthy of faith are the circumstances narrated of the martyrdom of St. Dasius, but his existence and condemnation are admissible; his body, venerated, was translated to Ancona and provided with a Greek inscription judged to be of the 5th century (F. Cumont, in Anal. Boll., 27 [1908], p. 370). A final martyr of Moesia would be the soldier Emiliano, condemned under Julian the Apostate for having damaged a pagan altar (F. Cabrol, V. BIBLICA.). Already before the edicts of Galerius, Constantine, and Licinius, which granted Christians the free exercise of their worship, Christian communities appear to have existed in several places in Moesia (Singidunum, Ratiaria, Durostorum, Axiopolis, Noviodunum, Tomi, Romuliana: Lactantius, De mortibus persecutorum, XI, 1). Once peace was granted to the Church by those edicts, episcopal hierarchies fully constituted are soon found in not a few cities of Moesia. Episcopal sees between the 4th and 6th centuries are at Viminacium, Marcianopolis, Singidunum, Margum, Ratiaria, Aquae, Castra Martis, Oescus, Sardica, Naissus, Remesiana, Pautalia, Iustiniana Prima, Iustiniana Secunda, Neutina, Diocletiana, Mariana, Zappara, Stobi. Names of bishops are preserved in the signatures of the Councils of Nicaea (325), of Ephesus (341), of Sardica (343), of Constantinople (381), and in other documents.
So flourishing a growth of Christianity, however, was not immune from heretical deviations; some bishops of Moesia found sympathy and following for the doctrines of Nestorius, but Arianism took especially strong root there, as attested by a letter of St. Ambrose (Epist., II), a passage of Sozomen (Hist. eccl., VII, 17), and the records of Arian bishops: Ursacius and Secundianus at Singidunum between 355 and 370, Domininus at Marcianopolis about the same time, and Auxentius at Durostorum after 380.