Let me relate to you a dialogue I once overheard.

Picture two children. One of them -- "Ray" I think his name was -- was visibly distressed by the revelation that his brother Brian no longer believed in Father Christmas.

- But you must believe! How can you not believe?

- Ray, don't you see it? There is no Father Christmas. It's just a fantasy!

- Well, if there's no Father Christmas, who gave you that shiny new Game Kit last Christmas?

- It says "Made in Taiwan" on the Kit. I don't think it came from the North Pole. You know, I snuck a peek into papa's wallet, and there was a receipt for a Game Kit. It's our parents who are giving us those presents.

- Well maybe Father Christmas put the receipt there! He's testing our faith!

- No, Ray. Look, I know you want to believe in Father Christmas, but just think about it! Father Christmas supposedly visits millions of households across the world in one evening! It's just not possible.

- Well maybe it's a miracle! You have to have faith!

- Ray...

- You're just denying Father Christmas because you want to be naughty!

- No, Ray. I don't want to be naughty, and I don't intend to. But there comes a time when we have to start being nice because it's the right thing to do rather that because we want presents.

- Brian, please! I'm begging you to believe! One day it'll be Christmas again and you'll get no presents! But then it'll be too late to repent!

- Ray...

Well okay, it wasn't really children and the imaginary friend they were talking about was not Father Christmas, but you get the idea.