This church, as the Cathedral, was the seat of administration of Mar Abraham. This cathedral is described as the biggest church, in ancient documents was renovated by Mar Abraham in 1570 without much change in its shape. After it was partially destroyed by Tipu, it was repaired several times.
Before the church was constructed, the place might have been a colony of the Jews. There are historical documents to prove the presence of the Jewish community here. The white and black Jews had separate synagogues. One of these groups might have embraced Christianity and Mar Abraham might have renovated one such synagogue into a church in due course. Bishop Francis Ross convened the Angamaly Synod at this church in 1583. This beautiful cathedral is a blend of the Syrian and Kerala styles of architecture. It has a large collection of idols carved in wood. Those of the Sorrowful Mother (Mater Dolorosa), St. Hormis, St. Mary, and St. Sebastian, as well as of the crucified Christ sculpted in 1906, keep to high standards.
The church was the venue for the famous meetings of churches of 1773. Paremakkal Governador stayed here and conducted administration. There are, in the church, stone slabs with inscriptions that bear testimony to his administration.The celebration of the Feast of St. Sebastian began in 1952 and since1988, the festival of St. Hormis is also being observed together with that of St. Sebastian. (Feroli, The Jesuits in Malabar, Souza, Faria, Oriente Conquistado, 1698, Vol. II)