The church of St. Thomas Christians is an Apostolic Church founded in India by St. Thomas, one of the twelve apostles of Christ. According to ancient, strong and continuous traditions, St. Thomas landed at Kodungalloor (Muziris) in 52 A.D. After preaching and establishing Christian communities in different parts of India, he suffered martyrdom at Mylapur in 72 A.D.
Tradition holds that St. Thomas founded seven churches in Kerala; at Kodungalloor, Niranam, Kollam, Chayal, Kottakkavu, Kokkamangalam and Palayoor. Even before the Christian era, there were Jewish colonies in South India and we see with amazement the strange coincidence that these seven churches are situated in or near these colonies. From early centuries the Church of St. Thomas Christians came into life-relation with the Christian communities that came to be known as East Syrian Church.This relationship made the St. Thomas Christians share the liturgical, spiritual and other ecclesiastical traditions with the East Syrian Church (therefore they are grouped under Chaldean Rite). At the same time the Christians of St. Thomas kept their distinctive character especially in Church administration and socio-cultural and ascetic-spiritual life.
Knanaya Catholics of Syro-Malabar Church claim their origin to Thomas of Cana and the 72 families that migrated to Kerala in 345 A.D. from the land of Syria. The descendants of this group maintained their separate identity. In the matter of liturgy and spiritual activities they fully belong to the Syro-Malabar Church and as such they are an integral part of it. His Holiness Pope Pius X established the diocese of Kottayam in Kerala for this endogamous group in 1911.
Though today the Syro-Malabarians are found mainly in the southern state of Kerala and in the big cities of India there are evidences to believe that there were communities of these Christian in other parts of India right from early centuries. For some reasons unknown to us, they ceased to exist. These Christians were well established and integrated in the fabric of the society at large. In the early centuries their main occupations are believed to have been military services to the local kings, trade or agriculture. However, this is no more so today.
The head of the Church of St. Thomas Christians assumed the title “The Metropolitan of All India”. A St. Thomas Christian priest with the title ‘Archdeacon of all India’ played the role of the effective leader of the community (Jathikkukarthavyan). The Archdeacon carried out the administration through general and local assemblies (Pallyogams). Their socio-cultural life was fully Indian and in their life of worship they adopted certain elements of this life. Their ascetic-spiritual life reflected Indo-oriental tradition. The sum total of this life was called the Law of St. Thomas (Mar Thoma Margam).
Because of the Portuguese colonization of parts of India in the late 15th and in the early 16th centuries and the consequent ecclesiastical arrangements, European bishops from the Latin Church were appointed to govern the St. Thomas Christians. Thus the Syro-Malabarians were very much influenced by the European Latin Christians. This is reflected both in the system of church administration as well as in the life of worship. The Latin influence led also to the gradual disappearance of the identity of the Syro-Malabarians as a separate individual Church. In other words, the Syro-Malabarians began to be considered as a group of Catholics following a different rite in a Latin diocese.