‘And after eight days again his disciples were within, and Thomas was with them. Jesus comes, the doors being shut, and stood among them and said, “Peace to you.” Then he says to Thomas, “Reach out here with your finger and see my hands, and reach out your hand and put it into my side and do not be doubtful but believing.” Thomas answered and said to him, “My Lord and my God.”
Eight days passed by with the disciples still excitedly discussing what had happened and Thomas still convinced that they had been having hallucinations. Then Jesus appeared again to them.
‘The doors being shut.' This probably indicates that they were locked. The only reason for this repeated mention is that John wants us to appreciate that Jesus suddenly appeared in a locked room. He does not dwell on the fact but he had noted it. The appearance was miraculous.
Jesus clearly knew what Thomas had been saying and responded graciously, although with a hint of reproof. There is no suggestion that Thomas finally demanded to do what he had previously said. Instead he declared, “My Lord and my God.”
This was the first open declaration of Jesus as God. It is the final step in the understanding that Jesus as ‘the holy One of God' (John 6:69) was indeed ‘God, the holy One'. That it is put on Thomas's previously doubting lips is demonstration of its genuineness. An inventor would have put it on the lips of Peter or John.
It is interesting that John brings out different moments of discernment, Peter in John 6:69; himself in John 20:8; and here Thomas. Sometimes one, sometimes another, reveal these moments of understanding and revelation when they have ‘outpaced' the others. Here the once-doubting Thomas leads the way.