In the 16th century when the Portuguese arrived on India's southwestern coast, they were astounded to find a thriving Christian church, tracing its roots back to the Apostle Thomas, who is believed to have brought Christianity to India in the year 52.

Today, there are seven million "St. Thomas Christians" in the southern Indian state of Kerala. However, although in their faith they share common origins and heritage, the Christians are divided into several denominations.

The denominations include the 3.3-million member Syro-Malabar (Catholic) Church, the Orthodox Church (with 2.5 million members in several different churches), the Mar Thoma Church (with 800,000 members) and the Syro-Malankara Church, which has 380,000 members and also comes under the jurisdiction of the Catholic Church.

All the churches take pride in their apostolic origin. Thomas, Jesus' "doubting" apostle, is believed to have arrived on the Arabian Sea coast of Kerala and died a martyr 20 years later in what now is the neighboring state of Tamil Nadu.

The church that traced its foundation back to Thomas was united until a revolt against the Portuguese missionaries in the 17th century. But even today, members of all these churches have much in common and are frequently described as "Hindu in culture, Oriental in worship and Christian in faith."

"Here's a vibrant apostolic church with a common history and heritage divided into several camps," according to K. M. George, a leading Orthodox theologian and principal of the Theological Seminary of the Malankara Orthodox Syrian Church at Kottayam in central Kerala.

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According to church historians, the church founded by Thomas developed a distinct identity over the centuries, assimilating Hindu traditions and practices ...