Simon Birch rot in Hell

Why do some great books wind up as celluloid drek? I realize they are different medium and ask different things of their viewers/readers, but c'mon, why eviscerate a story and then place it on the screen? Maybe that's why John Irving's hilarious and compelling novel was called A Prayer for Owen Meany and that treacly, aspartame-filled film it was based upon ended up titled Simon Birch.

The two bear some resemblance but not much: both take place in New Hampshire, both concern a diminutive title character, and both narrator's mothers have died in a baseball accident leaving the identity of the father a mystery.
All I remember from the movie was a treacly, feel-good message about believing in yourself or some such pop-pshych mush. The book, obviously, dwells much more deeply on themes of identity, destiny and providence, and friendship.
A book about a boy and his abnormally small friend who sees his own tombstone in a vision doesn't sound all that funny. To top it off Owen thinks he is an instrument of God. In spite of such a dour sounding synopsis this book is hilarious. I don't think I've laughed so much reading a book since Frank Schaeffer's Portofino.
Owen is highly intelligent and has a thing for his best friend's, the narrator, mother. Consider this brief passage from when Owen, due to his size, plays the infant Jesus in the local Episcopal church's Christmas play:

The combination of being so roughly handled by Barb Wiggin and discovering
that my grandmother had been free to attend the pageant--but had chosen not to attend--was deleterious to Owen's mood; he grew cranky and petulant. He insisted that he be unswaddled, and then reswaddled, in my mother's LUCKY scarf; when this was accomplished, the white cotton swathes could be wrapped over the scarf to conceal it. The point being, he wanted the scarf next to his
skin.
"FOR WARMTH AND FOR LUCK," he said.
"The Baby Jesus doesn't need 'luck,' Owen,"
Barb Wiggin told him.
"ARE YOU TELLING ME CHRIST WAS LUCKY?" Owen asked
her. "I WOULD SAY HE COULD HAVE USED A LITTLE
MORE LUCK THAN HE HAD.
I WOULD SAY HE RAN OUT OF LUCK, AT THE
END."
"But Owen," Rector Wiggin said. "He was
crucified, yet he rose from the dead--he was resurrected. Isn't the
point that he was saved?"
"HE WAS USED," said Owen Meany, who was in a
contrary mood.

If you're looking for something heavier than typical beach reading and yet lighter than say, Barth's treatise on Romans A Prayer for Owen Meany could make your late summer more enjoyable than Memphis-style ribs and Michigan-grown corn on the cob.
And for God's sake (or better yet, your own) stay away from that little bastard Simon Birch.