Malankara Orthodox Syrian Church

The Malankara Orthodox Syrian Church (MOSC) also known as the Indian Orthodox Church (IOC) or simply as the Malankara Church, is an autocephalous Oriental Orthodox church headquartered in Devalokam, near Kottayam, India. It serves India's Saint Thomas Christian (also known as Nasrani) population. According to tradition, these communities originated in the missions of Thomas the Apostle in the 1st century (circa 52 AD). It employs the Malankara Rite, an Indian form of the West Syriac liturgical rite.

The MOSC descends from the Malankara Church and its affiliation with the Syriac Orthodox Church. However, between 1909 and 1912, a schism over the authority of the Syriac Orthodox Patriarch of Antioch resulted in the dissolution of the unified Malankara Church and establishment of the overlapping and conflicting MOSC and Jacobite Syrian Christian Church (JSCC). Since 1912, the MOSC has maintained a catholicate, the Catholicos of the East and Malankara Metropolitan of Malankara Orthodox Church–presently Baselios Marthoma Mathews III–who is the primate of the church.

The MOSC drafted and formally adopted a constitution in 1934, in order to define the relationship it has with the Syriac Orthodox Church and the patriarch, wherein it defined itself a division of the Syriac Orthodox Church with its supreme spiritual leader being the Patriarch of Antioch. However the constitution stipulated that all the spiritual duties of the patriarch in the Malankara Church was entrusted to the Catholicos of the East and reiterated that its administration was the prerogative of the Malankara Metropolitan. The constitution further declared that the positions of the Catholicos of the East and Malankara Metropolitan are to be held by the same person from then on, who shall henceforth act as the spiritual and administrative head of the church. The Malankara Orthodox Syrian Church asserts communion with the other Oriental Orthodox churches. However, regular legal and occasional physical confrontations between the MOSC and the Syriac Orthodox JSCC have continued despite multiple efforts to reconcile the churches.

The Malankara Orthodox Syrian Church accepts miaphysitism, which holds that in the one person of Jesus Christ, divinity and humanity are united in one (μία, mia) nature (φύσις – "physis") without separation, without confusion, without alteration and without mixing where Christ is consubstantial with God the Father. Around 500 bishops within the Patriarchates of Alexandria, Antioch and Jerusalem refused to accept the dyophysitism (two natures) doctrine decreed by the 4th ecumenical council, the Council of Chalcedon in 451,^{[dubious – discuss]} an incident that resulted in the second major split in the main body of the Christian Church (after the Nestorian schism). While the Oriental Orthodox churches rejected the Chalcedonian definition, the sees that would later become the Catholic Church and the Eastern Orthodox Church accepted this council.

Self-reporting roughly 2.5 million members (with external estimates of roughly 1 million) across 32 dioceses worldwide, a significant proportion of the Malankara Orthodox Syrian Church's adherents reside in the southern India state of Kerala with the Malankara communities in North America, Europe, the Middle East, Malaysia, Singapore, Sri Lanka, South America, Australia and New Zealand.

According to tradition, Christianity first arrived in India with Thomas the Apostle during the 1st century AD, evolving into Saint Thomas Christianity over several centuries. While isolated and generally independent in administration, Indian Christians maintained contact with the Christian hierarchies of Antioch, Persia, and potentially Alexandria. The Saint Thomas Christians had relationships with the Persian Church of the East from at least the 6th century onward. The Indians inherited its East Syriac dialect for liturgical use and gradually became Syriac Christians in ritual and doctrine. They received clerical support from Persian bishops, who traveled to Kerala in merchant ships on the spice route. For much of this period, Saint Thomas Christians were under the leadership of an archdeacon (a native ecclesiastical head with temporal powers, deriving from the Greek arkhidiākonos).

During the 16th century, efforts by the Portuguese Padroado–an arm of the Catholic Church–to bring the Saint Thomas Christians under the administration of the Latin Church and attempts to Latinize the Malankara Rite led to the first of several rifts in the community. These divisions intensified following the 1599 Synod of Diamper. Saint Thomas Christians who were opposed to the Portuguese Padroado missionaries took the Coonan Cross Oath on 3 January 1653. The Dutch East India Company expulsion of the Portuguese from much of Malabar enabled the reconciliation of some Saint Thomas Christians and the Catholic Church, with this group eventually evolving into the Syro-Malabar Catholic Church, an Eastern Catholic church that adopted the Chaldean Catholic Church's East Syriac Rite and Diophysite christology.

Many Saint Thomas Christian chose to remain independent from the Catholic Church. Patriarch Gregorios Abdal Jaleel, the Syriac Orthodox Archbishop of Jerusalem, witnessed the 1665 ordination of Thomas as Bishop Thoma I, who forged a renewed relationship with the Syriac Orthodox Church of Antioch and Saint Thomas Christians, which laid the foundation for adopting West Syrian liturgy and practices over the next two centuries. Those who supported the indigenous church leader of Malankara, Thoma I, and adopted West Syrian liturgies and practices and Miaphysite faith evolved into the Malankara Church.