Didymos is the son of Ittyavira Thomas of Chiramel-Mulamootil House in Nedumbram near Thiruvalla and Sosamma of Chiramel House in Mavelikara. He joined the Tabor Dayara in Pathanapuram in 1939 where he completed his high school education. He passed his Intermediate from C.M.S College, Kottayam in 1945, his B.A from National College, Tiruchirapalli in 1951, his B.T from Maston Training College, Chennai in 1954, and his M.A from Christ Church College, Kanpur in 1961.
He completed his training for priesthood under the guidance of Thoma Mar Dionysius and Baselios Augen, Catholicose of the East. He received from Geevarghese II Catholicose of the East the order of Korooyo on 11 March 1942, full deaconship on 22 May 1947 and priesthood on 25 January 1950. He Has served as headmaster of Ponnayya High School, Thiruchirapalli and St. Stephen's High School, Pathanapuram, as Professor of English in St. Stephens College Pathanapuram, and as President of the Orthodox Youth Movement.
On 16 May 1965, Moran Mar Baselios Ougen I made him Ramban. The Malankara Syrian Christian Association, which met on 28 December 1965 at M.D Seminary, Kottayam, elected him to the office of Metropolitan. On 24 August 1966 at Kolencherry Baselios Ougen Bava consecrated him as Metropolitan Thomas Mar Timotheos.
He became the Metropolitan of Malabar Diocese on 11 November 1966. He continues to serve as the General Superior of Mount Tabor Dayara and Convent in Pathanapuram. On 10 September 1992, the Malankara Association, which met at Parumala, elected him as successor- designate to the Malankara Metropolitan and Catholicose of the East. Since being elevated to the Catholicate, has brought about positive changes throughout the church. He has been the first Catholicos to preside over an official church secretariat, which helps keep the administrative affairs of the church running efficiently. He also has plans to renovate the Catholicate Headquarters and bring it up to par with modern times and technology. He has encouraged unity in worship and discipline in all parishes. He has also made extensive Apostolic visits to the church's diaspora, tending to his flock in other regions.
He started his service to the Church as a monk when he was a teenager. He was called to the monastic life by the late Metropolitan Mar Dionysius of Niranam. The Malankara Orthodox Syrian Church has a tradition of selecting bishops from the monastic ranks, but due to period when there were no functioning monastic communities, this tradition could not always be followed. Mor Didimos is an exemption to our recently fabricated monasticism as a preparation to receive the episcopate.