What does John 20:20 mean?

While hiding in a locked room, the disciples are suddenly in the presence of Jesus (John 20:19). The last time most of these men had seen Him, He was being arrested (Matthew 26:56). A few had witnessed His trials (John 18:15), and at least one was there when He was crucified and murdered (John 19:25–27). His burial location was known (Matthew 27:60–61). It's possible that, if Jesus had appeared without any scars of any kind, they might have had later doubts about His physical resurrection.

Showing His crucifixion wounds reassures the men that this is the same Jesus, and the same body, which was executed on the cross. The same form that was in the grave is now alive. This meant His prophecies were fulfilled, exactly as He had said they would be (John 2:19–22; Mark 9:31; Luke 18:33). John's description of their response to this is probably greatly understated.

Even amid these miracles, the disciples show a frustrating level of hard-headedness. Mary Magdalene and other women had told them about seeing Jesus (John 20:16–18), but this did not stop them from hiding. Nor did it give them confidence (Luke 24:10–11). Only when they see Jesus with their own eyes, together, do they seem to accept the truth. In another instance of stubbornness, one of the disciples, Thomas, is not there. Despite the combined claims of the other disciples, and the women, he will refuse to accept that Jesus is alive until he personally sees and touches Him (John 20:24–25).