Jesus appeared to Thomas because of his doubt and disbelief; but Thomas was really looking/searching for the Truth and finally he found the Truth(Jesus Christ the Messiah) and the Truth could set him free from doubt, disbelief, misunderstanding and all evils in deeds and thoughts in life. Then he confessed his great faith in the Risen Christ and said " my Lord and my God" and believed in the Risen Lord is the Goal of human life in the creation of God and the Purpose of John's Gospel ...i wrote all these things so that you may believe in him and those who believe in him will have the eternal life.
May the Divine Mercy of God, the Risen Christ and the Holy Spirit forgive our sins, protect us from all evil and save us all from the coronavirus pandemic Covid-19. Amen
Wishing you A Happy Feast of the Divine Mercy Sunday!