From Wikipedia
Network executives were not happy with several aspects of the show, forcing Schulz to wage some serious battles to preserve his vision. The executives didn’t want to have Linus reciting the story of the birth of Christ from the Gospel of Luke; the network orthodoxy of the time assumed that viewers would not want to sit through passages of the King James Version of the Bible. But Schulz was adamant about keeping this scene in, remarking that “If we don’t tell the true meaning of Christmas, who will?”
That part is the highlight of the movie.
Good for Schultz for sticking to his guns.