St. Thomas was one of Christ's twelve Apostles. The name Thomas comes from Aram. "te'oma' ", meaning `twin'; John, in his Gospel uses the Greek version `Didymus' three times ( 11:16; 20:24; 21:2 ). Three important events in his life are recorded in the Gospels: when Thomas stated his readiness to die for the gospel (John 11:16 ); his question at the Last Supper drawing from Jesus the statement "I am the way, the truth and the life" (John 14:4-7 ); and perhaps his most famous incident of doubting giving him the nick-name "Doubting Thomas". Thomas was not present when Jesus appeared to the other disciples after the resurrection, he was sceptical about their reports of meeting the risen Christ stating "unless I see..., and touch..., I will not believe." Then a week later Jesus appeared among them again and Thomas was present, this time he gave a whole-hearted declaration of his belief in the risen Christ saying "My Lord and my God" (John 20:24-29 ) this made him the first person to openly declare Christ's divinity.

John is the only Gospel to give personal account of Thomas, the other three all make mention of him but only in the list of names of the Apostles. (Matthew 10:3, Mark 3:18, Luke 6:15). After the death and resurrection of Jesus Thomas is only mentioned one more time (Acts 1:12-14 ) when he is mentioned as one of the number who waited in Jerusalem after the ascension of Jesus where "They all joined together constantly in prayer, along with the women and Mary the mother of Jesus, and with his brothers."

Little is known about Thomas after the biblical events. As with many saints legends abound and attested and documented evidence is scarce. Eusebius states that Thomas sent St.Thaddeus to Edessa to baptize King Abgar and went himself to Parthia and "the Medes, Persians, Carmanians, Hyrcanians, Bactrians and other nations in those parts". Another tradition based on the Acta Thomae (The Acts of Thomas) states that Thomas went to India to the court of Gundafor a Parthian who ruled part of India. Or according to other traditions to the Malabar Coast where there is a population of Christians who are known as the "Christians of St.Thomas". There have been Christians there from early times and in their liturgy they use forms of a Syriac language derived from Mesopotamia and Persia. There are several medieval references to the tomb of St.Thomas in India. In 1522 the Portuguese discovered a tomb in Mylapore which was alleged to be the tomb of the Apostle, certain small relics from the tomb are now preserved in the Cathedral of St.Thomas in Mylapore. "But (according to Butler's Lives of Patron Saints - 1987) the bulk of his reputed relics were certainly at Edessa in the fourth century, and the Acta Thomae relate that they were taken from India to Mesopotamia. They were later translated from Edessa to the island of Khios in the Aegean, and from thene to Ortona in the Abruzzi, where they are still venerated."