What does Luke 24:40 mean?

Born-again believers (John 3:3–5) look forward to a glorified body in eternity (1 John 3:2). We don't know exactly what that will be like, but there are a few details. They will be imperishable (1 Corinthians 15:51–54): immune to being hot or cold, hungry or thirsty, sick or injured.

Jesus' glorified body carries the scars of the work He did on the cross. In His human form, His hands and feet still show signs of the nails that held Him to the cross. His side shows the evidence of the soldier's spear (John 20:27). In another form, He is the Lamb who was slain (Revelation 5:6).

When the risen Jesus appears to a room filled with His disciples, many have an extremely hard time believing it's Him. He shows them these scars to strengthen their faith.

There is someone missing from the room, however. For some reason, Thomas wasn't present. When he returns, later that night, he doesn't believe them. He insists that he won't believe unless he touches Jesus personally (John 20:25). He's not a coward. He agreed to follow Jesus to Jerusalem knowing the religious leaders might kill them all (John 11:16). And he's not unique in his disbelief. Many in the room at this moment are looking at Jesus and still don't believe.

Yet Thomas is extreme in His disbelief. He has the witness of more than a dozen of people and still refuses to believe. Only two witnesses are required in Jewish law. His skepticism borders on a cynical refusal to believe, no matter what.

In eight days, Jesus returns to the room, just for Thomas. Jesus will invite Thomas to touch His hands, feet, and side, just as Thomas demanded. He'll say, "Do not disbelieve, but believe." Thomas will respond the only way he can: "My Lord and my God!" Jesus will answer, "Have you believed because you have seen me? Blessed are those who have not seen and yet have believed" (John 20:26–29).