When Jesus first appeared within a locked room in Jerusalem, after the resurrection, Thomas the Apostle was not present. When informed that Jesus was alive again, Thomas said that he would not believe until he saw Jesus himself, and saw the wounds that Jesus had suffered during the crucifixion. About a week later, Jesus appears again the locked room, and Thomas inspects his crucifixion wounds. Thomas then confesses that Jesus is the Messiah and is God incarnate.
As explained in the Gospel of John:
24 But Thomas, one of the twelve, called Didymus, wasn’t with them when Jesus came. 25 The other disciples therefore said to him, “We have seen the Lord!”
But he said to them, “Unless I see in his hands the print of the nails, put my finger into the print of the nails, and put my hand into his side, I will not believe.”
26 After eight days, again his disciples were inside and Thomas was with them. Jesus came, the doors being locked, and stood in the middle, and said, “Peace be to you.” 27 Then he said to Thomas, “Reach here your finger, and see my hands. Reach here your hand, and put it into my side. Don’t be unbelieving, but believing.”
28 Thomas answered him, “My Lord and my God!” (John 20:24-28, WEB)
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