The Syro-Malabar Church was known as the Church Of The St. Thomas Christians until the 18th century because it was founded by St. Thomas, one of the apostles of Jesus Christ. St. Thomas came to India in 52 A.D. He preached the Word Of God and baptized a large number of local people. As a Church that existed outside the Roman Empire the Church of the St. Thomas Christians had little contact with the Roman or the other Churches within the Empire. At the same time it maintained communion with the Church Of Rome through the Church in the Persian Empire, which later became known as the East Syrian or Chaldean Church. It is believed that Christianity in the Persian Empire was introduced by the disciples of St. Thomas. It seems that the Christians in India had contact with these Christians of the Persian Empire from very early times. Given the commercial traffic across India in those days such contact could easily have been made.
In the middle of the 4th century, a group of Christians from these communities under the leadership of a merchant named Thomas of Kinagi migrated to the southern parts of India known as Kerala now. The descendants of the latter group are called Southists and the descendants of the former group, Northists. Both of them belong to the Syro-Malabar Church, but live as two separate communities, each with their own diocese and parishes. From at least the 8th century until the 16th century the Bishops of the Syro-Malabar Church were sent from the East Syrian Church, having been appointed by the Patriarch of the East Syrian Church. There is a tradition which says that there were Indian Bishops in the beginning. But there is very little written evidence which says anything concrete about them.
Because of the Portuguese colonization of parts of India in the early 16th century and of the consequent ecclesiastical arrangements, from 1600 onwards, European Bishops from the Latin Church were appointed by the Pope to govern the St. Thomas Christians. Their rule ended in 1896, in which year indigeneous Bishops from among the St. Thomas Christians were appointed to the now-styled “Syro-Malabar Church”. The Church was now raised to the dignity of a major archiepiscopal church. It currently has twenty five dioceses in India and a diocese in Chicago. It also runs different mission centers in different nations. The total number of Syro-Malabar Catholics is large and they live all over the world. This Church is blessed with many vocations to priesthood and the religious life, who witness to Christ all over the world.