Enthroned on 26 July 2002 by Patriarch Ignatius Zakka I Iwas in Damascus, Syria, he led the church through periods of ecclesiastical and social challenge until his death in 2024.

[2] Frequent illnesses interrupted his education, leading his mother to pray at the relics of St. Cyricus, St. Ignatius Elias III, and St. Gregorios of Parumala at Malecruz Dayro.

[2][3] Due to financial constraints, he left school after the fourth grade and began working as a mail runner with the postal department.

[2] Serving as vicar of St. Peter's and St. Paul's Church in Puthenkurish, he later ministered in communities including Vellathooval, Kezhumuri, Fort Cochin, Valamboor, Calcutta, and Thrissur.

Mor Baselios Thomas I died on 31 October 2024 at a medical facility in Kochi, at the age of 95, following a prolonged battle with age-related health issues.