Christians generally don't mind stories that drift a little from accepted beliefs if the changes make it a more uplifting pro-Christian story. For example, Jacob Marley (Scrooge's business partner) appeared as a ghost. Even if one said it was his soul that appeared, what would a soul be doing outside of heaven or hell? The Catholic interpretation treats Marley as someone in purgatory who can't get to heaven until he convinces Scrooge to change his ways. I don't think anyone would have a serious problem with his presence in the story, as written.
Same with "It's a Wonderful Life". An angel took the main character (I forget his name) to see an alternate vision of the future in which the character was present to watch but not interfere, much as Scrooge had to. How many Christians will object to the idea of angels with wings and the idea that an angel has to earn his wings? The idea of wings has been around since the 4th century but it's not in the Bible.
Very good points. I liked both stories.