Some icons depicting this event are inscribed “The Doubting Thomas.” This is incorrect. In Greek, the inscription reads, “The Touching of Thomas.” The Slavonic inscription is, “The Belief of Thomas.” When Saint Thomas touched the Life-giving side of the Lord, he no longer had any doubts.
This day is also known as “Antipascha.” This does not mean “opposed to Pascha,” but “in place of Pascha.” Beginning with this first Sunday after Pascha, the Church dedicates every Sunday of the year to the Lord’s Resurrection. Sunday is called “Resurrection” in Russian, and “the Lord’s Day” in Greek…taken from https://www.oca.org/saints/lives/2024/05/12/34-antipascha-saint-thomas-sunday
