The Syro-Malabar Church is one of the 23 Eastern Catholic Churches in full communion with the Pope, tracing its origins to the evangelistic mission of St. Thomas the Apostle in Kerala, India, in the 1st century AD. They are part of the larger body of St. Thomas Christians (also known as Nasranis) and represent a unique blend of ancient East Syriac liturgical traditions and local Indian culture.

Historically, the St. Thomas Christians maintained ecclesiastical ties with the Church of the East (Persian Church), adopting its East Syriac Rite and customs. This connection led to the development of a distinct liturgical and theological heritage. Their social structure was traditionally endogamous, with a strong emphasis on community identity and a high social standing within Kerala society, often alongside Nairs and Nambudiris.

A significant turning point in their history was the arrival of Portuguese missionaries in the 16th century. The Portuguese attempted to Latinize the St. Thomas Christians, leading to tensions and ultimately the Coonan Cross Oath in 1653, where a large section vowed never to submit to Portuguese ecclesiastical authority. This event led to a schism, with one group eventually forming the Syro-Malabar Church (remaining in communion with Rome but retaining their East Syriac Rite) and another group, the Malankara Church, which later split into various denominations like the Jacobite Syrian Christian Church, Malankara Orthodox Syrian Church, and Syro-Malankara Catholic Church.

Today, the Syro-Malabar Church is the second-largest Eastern Catholic Church and a major Christian community in India, with a significant diaspora worldwide. They are known for their vibrant faith, strong family values, and contributions to education and healthcare. Their unique identity is rooted in their apostolic heritage, East Syriac liturgy, and deep integration into the cultural fabric of Kerala.