Question:If Jesus said that dead people cannot come back to earth, how did He raise Lazarus and some other people?
"So man lies down and does not rise. Till the heavens are no more, They will not awake Nor be roused from their sleep" (Job 14:12).
"And as it is appointed for men to die once, but after this the judgment" (Hebrews 9:27).
The general rule has always been that people live, die, and then await the judgment of God. This is the natural order of the world; thus, when Jesus raised Lazarus from the dead it was a miracle -- an event that went against the natural laws. The birth of a baby is a wondrous event, but it isn't a miracle because babies usually are born; it follows the natural order established by God. For the same reason, if people typically or often came back from the dead, then the raising of the widow's son at Nain or the raising of Lazarus would not be notable events.
Ultimately, Jesus himself came back from death. Unlike the others, he returned never to die again. "Now if Christ is preached that He has been raised from the dead, how do some among you say that there is no resurrection of the dead? But if there is no resurrection of the dead, then Christ is not risen. And if Christ is not risen, then our preaching is empty and your faith is also empty" (I Corinthians 15:12-14). The resurrection of the dead is a core doctrine of Christianity.