Although God had made clear through His angelic messengers first thing that morning, the Jewish day of First Fruits, that Jesus had risen from the dead, it wasn’t as clear to His followers as we imagine it must have been. Those visions quickly gave way to the reality that Jesus’ body was gone, and since they couldn’t yet understand the nature of His resurrection body—for He was the first fruits from the dead—the only rational thing that made sense to them was that someone must have removed His body. Even after His appearances to the two Marys, and to Peter, and to the two disciples on the road to Emmaus, the majority of His apostles couldn’t believe His crucified body that had been drained of its life fluids could ever live again—about which they were correct in the only way they could imagine it. But that’s where their faith was lacking, for they didn’t account that the power of God was able to do more, much more, than they could ever imagine, which is the lesson for us; cf. Mat 19:26, Mar 9:22-23, Luk 17:6. In light of their failure to stand up for Him at His arrest and trial that ended in His crucifixion, and now their hardness of heart to believe those who had seen Him, as well as their external fears that they too could be subject to arrest by the Jewish leaders, we especially hear the voice of our Shepherd God who came to seek and to save the lost when the first thing He said to them was, “Peace to you”.
Although Jesus’ words would before long produce their desired effect, because the group was convinced there was no way He could actually be alive, what effect did His sudden appearance still have upon them? See Luk 24:37 and note that both startled and frightened in the NAS communicate that they were terrified, as each of the words may also be translated. Again, in light of their mistaken belief that Jesus’ body could not really be alive, why does Luke say that they were so terrified? Is it possible that many of our fears that terrify us are actually caused by our own mistaken beliefs? If so, then what is the obvious way to correct our beliefs so as to overcome those fears? Cf. Jos 1:8-9.
What does Luke say their mistaken belief caused them to suppose they were seeing, which so terrified them? Note that some versions (NIV, NET, NRS) translate spirit as ghost, both words communicating the manifestation of a noncorporeal being to our senses. Such an appearance, like those mentioned throughout Scripture of angels, and of which Jesus’ appearance here was similar (cf. Luk 20:35-36), would naturally evoke great fear by its extraordinary nature. On what other occasion did Jesus surprise His disciples so that they thought they were seeing a ghost? See Mat 14:26-27, and note that a different word for ghost was used there, φάντασμα, from which we get our phantom. Also note in this pre-resurrection miracle that their fright and supposition that it must be a ghost was from the extraordinary nature of Jesus walking on the water, not because His body was actually ghost-like, which the context makes clear it was not. What does this teach us about the possibility of a mortal body (like both Jesus’ and Peter’s that walked on the water) to transcend what we consider normal physical laws, as opposed to those laws being so inviolable that to transgress them would require some change in the physical body so as to no longer be subject to them? Compared to that incident, how was His resurrection body that now startled them in fact materially different from that which walked upon the water? Although it wasn’t a disembodied ghost or spirit, how was it also not like the only bodies they knew? See 1Co 15:37,42-44 and note that the spiritual body that is raised from the natural body that is sown in death is necessarily different from a spirit that has no body. See also Luk 20:35-36, 24:15-16,31, Joh 20:15.
Consider that all people who have died since the creation of the world, except for Jesus, presently have no body; their physical body lies dead and decaying, or completely decayed, in the grave. At death, the souls of those who die in Christ go to be with Him (2Co 5:8, Phil 1:20-24, 1Th 4:14), but they are disembodied, and will have no spiritual body like Jesus’ until their resurrection when He returns. Demons are another example of the disembodied, different in nature from angels; cf. Act 23:8-9. As explained in the book of Enoch, first century Jews understood them to be the spirits of the Nephilim, powerful giants who were the half-breed offspring of rebellious angels (“sons of God”) with “the daughters of men”; see Gen 6:1-4. They were commonly referred to as unclean spirits, perhaps because of their origin from a forbidden, unnatural union; see Mat 10:1, 1Co 7:14, Jud 1:6-7. Like mortal men the bodies of the Nephilim died in the flood, but like angels who cannot die, they were not subject to the same death and corruption as men and so were still able to interact with the physical world in ways that the souls of dead men cannot (think poltergeists); cf. Mat 8:28-29, Mar 1:24, 9:25, Luk 4:33-34, 6:18, 8:27-31, Act 8:7. Because in their former state these unclean spirits possessed a physical body, they naturally seek to possess a similar habitation by overpowering a human soul, such as through occult or immoral allurements, to take control of their physical body; cf. Mat 12:43-44. With such an understanding, it is easy to see why the apostles would be terrified by what they imagined couldn’t be Jesus but such a manifesting spirit.