The Orthodox Church observes the Sunday of Thomas one week following the celebration of the Sunday of Holy Pascha. The day commemorates the appearance of Christ to His disciples on the evening of the Sunday following Passover. It also commemorates the appearance of the Lord to His disciples eight days later when Thomas was present and proclaimed "My Lord and my God" upon seeing the hands and side of Christ.

This Sunday is also called Antipascha (meaning "in the stead of Pascha," not "in opposition to Pascha") because with this day, the first Sunday after Pascha, the Church consecrates every Sunday of the year to the commemoration of Pascha, that is, the Resurrection.

Saint Thomas the Apostle is commemorated by the Church on October 6.