Didymos I was the son of Ittyavira Thomas of Chiramel-Mulamootil House in Nedumbram near Thiruvalla and Sosamma of Chiramel House in Mavelikara. At the age of 18, he joined Mount Tabor Dayara in Pathanapuram in 1939 as the disciple of Thoma Mar Dionysius, Metropolitan of Niranam where he completed his high school education. In his speeches, Didymos I used to say that his parents who led lives of prayer and munificence were his first role models.
As Rev. Fr. C. T. Thomas, he served as headmaster of Ponnayya High School, Thiruchirapalli and St. Stephens School, Pathanapuram. Within a year of taking charge as the headmaster of Ponnayya High School, Rev. Fr. C. T. Thomas was able to quadruple the pass percentage of students, who were chiefly the poor children from marginalized families. Later, Fr. C. T. Thomas also served as Professor and Head of the Department of English at St. Stephen's College, Pathanapuram, as well as the vice-principal of the College and as President of the Orthodox Youth Movement.
Priesthood
C. T. Thomas 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. He completed his training for priesthood under the guidance of Thoma Mar Dionysius and Baselios Augen, Catholicos of the East. Geevarghese II Catholicos ordained him to the order of quroyo on 11 March 1942 at Karapuzha Mar Gregorios Chapel. Full deacon on 22 May 1947 at Thiruvalla Bethany Aramana Chapel and priest on 25 January 1950 at Pathanapuram Mount Tabor Dayara.
Presbyterate
On 16 May 1965, Catholicos of the East Moran Mar Baselios Augen I ordained him Ramban at Mount Tabor Dayara. The Malankara Syrian Christian Association which convened at Kottayam M. D. Seminary on 28 December 1965 and elected him to the office of Metropolitan along with four others priests, following the ancient tradition of, selecting bishops from the monastic ranks. On 24 August 1966 at Kolencherry, the Catholicos Baselios Augen I ordained him as Metropolitan Thomas Mar Timotheos, along with Dr. Philipose Mar Theophilos and Yuhanon Mar Severios. Following the order of the Catholicos, Mar Thimotheos became the assistant Metropolitan of Malabar Diocese on 11 November 1966. Pathrose Mar Osthathios, the Metropolitan of Malabar, died on 2 February 1968. Mar Thimotheos succeeded him as the Metropolitan of Malabar Diocese.
Papacy
Mar Thimotheos became the Metropolitan of Malabar Diocese in 1968. He continued to be the General Superior of Mount Tabor Dayara and Convent in Pathanapuram until 2014. On 10 September 1992 the Malankara Association was convened at Parumala Seminary and elected him as successor-designate to the Malankara Metropolitan and Catholicos of the East. Due to old age, the Catholicos Baselios Marthoma Mathews II decided to abdicate the throne in 2005. On 29 October 2005, Mar Thimotheos assumed the office of Malankara Metropolitan, and was installed as the Catholicos of the East Baselios Marthoma Didymos I on 31 October 2005 by his predecessor Mathews II.Didymos I was the first Catholicos of the East to be enthroned by his predecessor. The enthronement took place at Parumala Seminary on 31 October 2005 at the age of 84. In addition to convening five sessions of Malankara Association, Didymos I ordained 14 Metropolitan Bishops. During the reign of Didymos I, the strength of the Episcopal Synod became 33, the highest till date. Didymos I had, as a priest, attended the consecration of holy Myron' officiated by Baselios Geevarghese II in 1951. Later, as a Metropolitan, Didymos I was a co-celebrant in the consecration of holy Myron on four occasions. As the Catholicos of the East, Didymos I himself officiated in the consecration of Holy Myron at Devalokam Catholicate Palace on 5 April 2009. Following the Church's tradition of honoring eminent prelates of the past, Didymos I bestowed the title "Sabha-Thejas" ' on Malankara Metropolitan Mar Dionysius V. The ancient churches declared as pilgrimage centers by Didymos I include St Mary's Orthodox Church, Kallooppara and St. George Orthodox Church, Cheppad. He visited Church members abroad.
Administrational reforms
Didymos I was the first Catholicos to preside over an official church secretariat, which administers to the affairs of the church. He also introduced progressive reforms in the administration of parishes, including the right for ladies of the congregations to participate in the parish assemblies . Some of the larger dioceses were divided creating new dioceses, in order to ensure more effective pastoral care and administration.
Didymos I abdicated the throne on 31 October 2010, at the age of 89. The following day he enthroned his successor Baselios Marthoma Paulose II as the Catholicos of the East. Didymos I spent the rest of his life at the Catholicate Palace. On 21 February 2014 he was given the Holy Anointing Service by Paulose II. Didymos I died on 26 May 2014 and was buried on 28 May 2014 at Mount Tabor Dayara, Pathanapuram, the monastery which he called his home.
Succession
Books
Didymos I wrote three books in Malayalam with the titles ജീവിതം സംസാരിക്കുന്നു, ഒരു മഹര്ഷി സംസാരിക്കുന്നു and ശുശ്രൂഷാ നടപടിച്ചട്ടങ്ങള്.
