The church, though modern in its vision and outlook, keeps the traditional Orthodox faith and liturgy. It accepts the first three ecumenical synods. The liturgy now in use is the translation of the Syrian liturgy adopted from the Syrian Orthodox Church in the 17th century.
The Indian Church was related to the Persian church in the early centuries, and the Persian church furnished bishops to India. This relationship halted at a later period. The Portuguese who colonized India in 1498 also tried to convert the local Christians to Catholicism. In 1599 they succeeded in forcibly converting some to the Roman Catholic Church. But in 1653, the St. Thomas Christians broke the shackles of foreign authority, as it is against the basic Orthodox tradition. Some people remained with the Catholic Church, and their descendants still belong to the Roman Catholic Church in India.
Later in the 19th century, the English also tried to convert the whole church into a reformed one, but in vain. However they were able to convert a few to the Anglican church. Even after such splits in the church, the Indian Orthodox Church remains the stronghold of Oriental orthodoxy in the sub-continent.
The church has a theological seminary at Kottayam, Kerala which was established in 1815.
The church take part active roles in various ecumenical activities at national and international levels. It is a member of the World Council of Churches. Famous theologians Mar Paulose Gregorious, Mar Geevarghese Osthathios are bishops of the Indian church. Rev. Fr.V.C. Samuel, who contributed a lot to the negotiations between the Oriental and Byzantine churches also belongs to this church.