Why?

 As they were talking about these things, Jesus himself stood among them, and said to them, “Peace to you!” But they were startled and frightened and thought they saw a spirit. And he said to them, “Why are you troubled, and why do doubts arise in your hearts? See my hands and my feet, that it is I myself. Touch me, and see. For a spirit does not have flesh and bones as you see that I have.” And when he had said this, he showed them his hands and his feet. And while they still disbelieved for joy and were marveling, he said to them, “Have you anything here to eat?” They gave him a piece of broiled fish, and he took it and ate before them. (Luke 24:36-43 ESV)
This is the big question of the chapter. Why do you seek the living among the dead? Why are you so slow of heart to believe? Why are you still confused and doubtful even now?  Like Peter's failed attempt to walk on water, Jesus still rightly asks not only "Why DID you doubt?", but "Why are you still doubting?"  Seeing is not believing.  We are waiting for something else... the One who will help us understand that all His Words are true, just as He said.  Without the Holy Spirit all the facts still do not add up. We need Him.