This is the question, "Why did not our Saviour show Himself after His resurrection to all the people? why only to witnesses chosen before of God?" and this is my answer: "Because this was the most effectual means of propagating His religion through the world."
After His resurrection, He said to His disciples, "Go, convert all nations:" [Matt. xxviii. 19.] this was His especial charge. If, then, there are grounds for thinking that, by showing Himself to a few rather than to many, He was more surely advancing this great object, the propagation of the Gospel, this is a sufficient reason for our Lord's having so ordained; and let us thankfully receive His dispensation, as He has given it.
Now consider what would have been the probable effect of a public exhibition of His resurrection. Let us suppose that our Saviour had shown Himself as openly as before He suffered; preaching in the Temple and in the streets of the city; traversing the land with His Apostles, and with multitudes following to see the miracles which He did. What would have been the effect of this? Of course, what it had already been. His former miracles had not effectually moved the body of the people; and, doubtless, this miracle too would have left them as it found them, or worse than before. They might have been more startled at the time; but why should this amazement last? ... Had our Lord appeared in public, yet few could have touched Him, and certified themselves it was He Himself. Few, comparatively, in a great multitude could so have seen Him both before and after His death, as to be adequate witnesses of the reality of the miracle. It would have been open to the greater number of them still to deny that He was risen. This is the very feeling St. Matthew records. When He appeared on a mountain in Galilee to His apostles and others, as it would seem (perhaps the five hundred brethren mentioned by St. Paul), "some doubted" whether it were He. How could it be otherwise? these had no means of ascertaining that they really saw Him who had been crucified, dead, and buried. Others, admitting it was Jesus, would have denied that He ever died. Not having seen Him dead on the cross, they might have pretended He was taken down thence before life was extinct, and so restored. This supposition would be a sufficient excuse to those who wished not to believe. And the more ignorant part would fancy they had seen a spirit without flesh and bones as man has. They would have resolved the miracle into a magical illusion, as the Pharisees had done before, when they ascribed His works to Beelzebub; and would have been rendered no better or more religious by the sight of Him, than the common people are now-a-days by tales of apparitions and witches.