The Church of South India (CSI) was officially formed on September 27, 1947, as a union of multiple Protestant denominations in South India. This historic event brought together Anglican, Presbyterian, Congregationalist, and Methodist churches into one unified body.

The idea of such a union was first proposed at the Tranquebar Conference in 1919, where church leaders envisioned a united Christian church in India. Over the next 28 years, extensive discussions took place among various denominational churches, all of which had been established by different missionary societies across the region.

Finally, after India gained independence, representatives of these churches agreed to unite and form the Church of South India. The inaugural ceremony was held at St. George’s Cathedral, Madras (now Chennai), and was presided over by Rt. Revd. C. K. Jacob, the bishop of the Anglican Diocese of Travancore and Cochin.

The CSI is now one of the largest Protestant denominations in India, with a membership of nearly four million. It is a member of the Anglican Communion, World Methodist Council, and World Communion of Reformed Churches.