Bingowings said:
he needs to believe in the Force that surrounds him because he is more than just a bag of flesh.
Ugly, giant bag of mostly water!
The cave scene always confused me to some extent as a tyke; why was Luke seeing his own face in Vader's helmet? I didn't think in terms of fear/belief/etc... at the time. And now I see that even as adults, there's no clearcut answer, based on the number of opinions there are. ;)