From Christian Prayer:
Saint Thomas is remembered for his incredulity concerning Christ’s resurrection from the dead. When confronted by the risen Lord, his disbelief gave way to belief and he proclaimed the Easter faith of the Church: “My Lord and my God!” Nothing certain is known of his life except for this evidence in the gospels. He is said to have subsequently preached the Gospel to the people of India. Since the fourth century the celebration of the transference of his body to Edessa has been commemorated on July 3.
The Prayer from Morning and Evening Prayer for the Feast of Saint Thomas, Apostle:
as we honour Thomas the apostle,
let us always experience the help of his prayers.
May we have eternal life by believing in Jesus,
whom Thomas acknowledged as Lord,
for his lives and reigns with you and the Holy Spirit,
one God, for ever and ever.