The history of Christianity in Romania began within the Roman province of Lower Moesia, where many Christians were martyred at the end of the 3rd century. Evidence of Christian communities has been found in the territory of modern Romania at over a hundred archaeological sites from the 3rd and 4th centuries. However, sources from the 7th and 10th centuries are so scarce that Christianity seems to have diminished during this period.

The vast majority of Romanians are adherent to the Eastern Orthodox Church, while most other populations that speak Romance languages follow the Catholic Church. The basic Christian terminology in Romanian is of Latin origin, though the Romanians, referred to as Vlachs in medieval sources, borrowed numerous South Slavic terms due to the adoption of the liturgy officiated in Old Church Slavonic. The earliest Romanian translations of religious texts appeared in the 15th century, and the first complete translation of the Bible was published in 1688.

The oldest proof that an Orthodox church hierarchy existed among the Romanians north of the river Danube is a papal bull of 1234. In the territories east and south of the Carpathian Mountains, two metropolitan sees subordinate to the Ecumenical Patriarch of Constantinople were set up after the foundation of two principalities, Wallachia and Moldavia in the 14th century. The growth of monasticism in Moldavia provided a historical link between the 14th-century Hesychast revival and the modern development of the monastic tradition in Eastern Europe. Orthodoxy was for centuries only tolerated in the regions west of the Carpathians where Roman Catholic dioceses were established within the Kingdom of Hungary in the 11th century. In these territories, transformed into the Principality of Transylvania in the 16th century, four "received religions" – Catholicism, Calvinism, Lutheranism, and Unitarianism – were granted a privileged status. After the principality was annexed by the Habsburg Empire, a part of the local Orthodox clergy declared the union with Rome in 1698.

The autocephaly of the Romanian Orthodox Church was canonically recognized in 1885, years after the union of Wallachia and Moldavia into Romania. The Orthodox Church and the Romanian Church United with Rome were declared national churches in 1923. The Communist authorities abolished the latter, and the former was subordinated to the government in 1948. The Uniate Church was reestablished when the Communist regime collapsed in 1989. Now the Constitution of Romania emphasizes churches' autonomy from the state.

Pre-Christian religions

The religion of the Getae, an Indo-European people inhabiting the Lower Danube region in antiquity, was characterized by a belief in the immortality of the soul.Treptow et al. 1997, p. 20.Treptow, Popa 1996, p. 98. Another major feature of this religion was the cult of Zalmoxis; followers of Zalmoxis communicated with him by human sacrifice.

Modern Dobruja – the territory between the river Danube and the Black Sea – was annexed to the Roman province of Moesia in 46 AD.Treptow et al. 1997, p. 28.Treptow, Popa 1996, p. 88. Cults of Greek gods remained prevalent in this area, even after the conquest.MacKendrick 1975, pp. 23, 192. Modern Banat, Oltenia, and Transylvania were transformed into the Roman province of "Dacia Traiana" in 106.Treptow, Popa 1996, pp. 84–85, 201. Due to massive colonization, cults originating in the empire's other provinces entered Dacia.Treptow, Popa 1996, p. 85.Pop et al. 2005, pp. 173–175. Around 73% of all epigraphic monuments at this time were dedicated to Graeco-Roman gods.Pop et al. 2006, p. 94.

The province of "Dacia Traiana" was dissolved in the 270s. Modern Dobruja became a separate province under the name of Scythia Minor in 297.Păcurariu 2007, p. 187Pop et al. 2006, p. 103.

Origin of the Romanians' Christianity

The oldest proof that an Orthodox church hierarchy existed among the Romanians north of the river Danube is a papal bull of 1234. In the territories east and south of the Carpathian Mountains, two metropolitan sees subordinate to the Ecumenical Patriarch of Constantinople were set up after the foundation of two principalities, Wallachia and Moldavia in the 14th century. The growth of monasticism in Moldavia provided a historical link between the 14th-century Hesychast revival and the modern development of the monastic tradition in Eastern Europe. Orthodoxy was for centuries only tolerated in the regions west of the Carpathians where Roman Catholic dioceses were established within the Kingdom of Hungary in the 11th century. In these territories, transformed into the Principality of Transylvania in the 16th century, four "received religions" – Calvinism, Catholicism, Lutheranism, and Unitarianism – were granted a privileged status. After the principality was annexed by the Habsburg Empire, a part of the local Orthodox clergy declared the union with Rome in 1698.

The core religious vocabulary of the Romanian language originated from Latin.Treptow et al. 1997, p. 45. Christian words that have been preserved from Latin include a boteza ("to baptize"), Paște ("Easter"), preot ("priest"), and cruce ("cross").Georgescu 1991, p. 11.Spinei 2009, p. 269. Some words, such as biserică ("church", from basilica) and Dumnezeu ("God", from Domine Deus), are independent of their synonyms in other Romance languages.

The exclusive presence in Romanian language of Latin vocabulary for concepts of Christian faith may indicate the antiquity of Daco-Roman Christianity;H. Mihăescu (1979): La langue latine dans le sud-est de l'Europe, București, p. 227, nr. 206Constantin C. Petolescu (2010): "Dacia – Un mileniu de istorie", Ed. Academiei Române, p. 358; some examples are:

The same is true for the Christian denominations of the main Christian holidays: Crăciun ("Christmas") (from or rather from ) and Paște ("Easter") (from ); Several archaic or popular saint names, sometimes found as elements in place names, also seem to derive from Latin: , and . Today, sfânt, of Slavic origin, is the usual way to refer to saint.

The Romanian language also adopted many Slavic religious terms. For example, words like duh ("soul, spirit"), iad ("hell"), rai ("paradise"), grijanie ("Holy Communion"), popă ("priest"), slujbă ("church service") and taină ("mystery, sacrament") are of South Slavic origin. Even some terms of Greek and Latin origin, such as călugar ("monk") and Rusalii ("Whitsuntide"), entered Romanian through Slavic. Several terms relating to church hierarchy, such as episcop ("bishop"), arhiepiscop ("archbishop"), ierarh ("hierarch"), mitropolit ("archbishop"), came from Medieval or Byzantine Greek, sometimes partly through a South Slavic intermediate A smaller number of religious terms were borrowed from Hungarian, for instance mântuire (salvation) and pildă (parable).

Several theories exist regarding the origin of Christianity in Romania.Boia 2001, p. 11.Niculescu 2007, p. 151.Keul 1994, pp. 16, 23. Those who think that the Romanians descended from the inhabitants of "Dacia Traiana" suggest that the spread of Christianity coincided with the formation of the Romanian nation.Keul 1994, p. 17. Their ancestors' Romanization and Christianization, a direct result of the contact between the native Dacians and the Roman colonists, lasted for several centuries.Păcurariu 2007, p. 189. According to historian Ioan-Aurel Pop, Romanians were the first to adopt Christianity among the peoples who now inhabit the territories bordering Romania.Pop 1996, p. 39. They adopted Slavonic liturgy when it was introduced in the neighboring First Bulgarian Empire and Kievan Rus' in the 9th and 10th centuries.Spinei 2009, p. 104. According to a concurring scholarly theory, the Romanians' ancestors turned to Christianity in the provinces to the south of the Danube (in present-day Bulgaria and Serbia) after it was legalized throughout the Roman Empire in 313.Schramm 1997, pp. 276–277, 333–335. They adopted the Slavonic liturgy during the First Bulgarian Empire before their migration to the territory of modern Romania began in the 11th or 12th century.Schramm 1997, pp. 337–338.

Roman times

Christian communities in Romania date at least from the 3rd century.Cunningham 1999, p. 100.Madgearu 2004, p. 41Zugravu 1995–1996, p. 165 According to an oral history first recorded by Hippolytus of Rome in the early 3rd century, Jesus Christ's teachings were first propagated in "Scythia" by Saint Andrew.Păcurariu 2007, p. 186. If "Scythia" refers to Scythia Minor, and not to the Crimea as has been claimed by the Russian Orthodox Church, Christianity in Romania can be considered of apostolic origin.

The existence of Christian communities in Dacia Traiana is disputed.MacKendrick 1975, p. 187. Some Christian objects found there are dated from the 3rd century, preceding the Roman withdrawal from the region.Pop et al. 2005, pp. 186–187. Vessels with the sign of the cross, fish, grape stalks, and other Christian symbols were discovered in Ulpia Traiana, Porolissum, Potaissa, Apulum, Romula, and Gherla, among other settlements. A gem representing the Good Shepherd was found at Potaissa. On a funerary altar in Napoca the sign of the cross was carved inside the letter "O" of the original pagan inscription of the monument, and pagan monuments that were later Christianized were also found at Ampelum and Potaissa.Pop et al. 2005, p. 188. A turquoise and gold ring with the inscription "" ("I am Jupiter's scourge against the dissolute Christians") was also found and may be related to the Christian persecutions during the 3rd century.

In Scythia Minor, a large number of Christians were martyred during the Diocletianic Persecution at the turn of the 3rd and 4th centuries. Four martyrs' relics were discovered in a crypt at Niculițel, with their names written in Greek on the crypt's inner wall.Pop et al. 2006, p. 115. Thirty-five basilicas built between the 4th and 6th centuries have been discovered in the main towns of the province.Păcurariu 2007, p. 188.MacKendrick 1995, pp. 172–174. The earliest basilica, built north of the Lower Danube, was erected at Sucidava (now Celei), in one of the Roman forts rebuilt under Justinian I (527–565).MacKendrick 1975, pp. 165–166.Niculescu 2007, p. 152. Burial chambers were built in Callatis (now Mangalia), Capidava, and other towns of Scythia Minor during the 6th century. The walls were painted with quotes from Psalms.Curta 2006, p. 48.

Clerics from Scythia Minor were involved in the theological controversies debated at the first four Ecumenical Councils. Saint Bretanion defended the Orthodox faith against Arianism in the 360s.Sozomen, Ecclesiastical History, Book VI, Chapter XXI. The metropolitans of the province who supervised fourteen bishops by the end of the 5th century had their See in Tomis (modernly Constanța). The last metropolitan was mentioned in the 6th century, before Scythia Minor fell to the Avars and Sclavenes who destroyed the forts on the Lower Danube.Stephenson 2000, p. 64.MacKendrick 1995, pp. 166, 210, 220–222. John Cassian (360–435), Dionysius Exiguus (470–574) and Joannes Maxentius (leader of the so-called Scythian Monks) lived in Scythia Minor and contributed to its Christianization.Mircea Păcurariu, "Sfinți daco-români și români", Editura Mitropoliei Moldovei și Bucovinei, (Iași, 1994)

Early Middle Ages

East Roman Empire period