But they were terrified and affrighted, and supposed that they had seen a spirit.

Jamieson-Fausset-Brown Bible Commentary

37, 38. a spirit-the ghost of their dead Lord, but not Himself in the body (Ac 12:15; Mt 14:26).

thoughts-rather, "reasonings"; that is, whether He were risen or no, and whether this was His very self.

Matthew Henry's Concise Commentary

24:36-49 Jesus appeared in a miraculous manner, assuring the disciples of his peace, though they had so lately forsaken him, and promising spiritual peace with every blessing. Many troublesome thoughts which disquiet our minds, rise from mistakes concerning Christ. All the troublesome thoughts which rise in our hearts at any time, are known to the Lord Jesus, and are displeasing to him. He spake with them on their unreasonable unbelief. Nothing had passed but what was foretold by the prophets, and necessary for the salvation of sinners. And now all men should be taught the nature and necessity of repentance, in order to the forgiveness of their sins. And these blessings were to be sought for, by faith in the name of Jesus. Christ by his Spirit works on the minds of men. Even good men need to have their understandings opened. But that we may have right thoughts of Christ, there needs no more than to be made to understand the Scriptures.