The Malankara Mar Thoma Syrian Church, often shortened to Mar Thoma Church, and known also as the Reformed Syrian Church and the Mar Thoma Syrian Church of Malabar, is an autonomous Oriental Protestant Christian church based in Kerala, India. While continuing many of the Syriac high church practices, the church is Protestant in its theology and doctrines. It employs a reformed variant of the West Syriac Rite Divine Liturgy of Saint James, translated to Malayalam.

The term Eastern Protestant Christianity encompasses a range of heterogeneous Protestant Christian denominations that developed outside of the Occident, from the latter half of the nineteenth century, and yet retain certain elements of Eastern Christianity. Some of these denominations came into existence when active Protestant churches adopted reformational variants of Eastern and Oriental Orthodox liturgy and worship, while others are the result of reformations of Orthodox beliefs and practices, inspired by the teachings of Western Protestant missionaries.