if I may boldly recommend the most wonderful Christmas book for you to read to Rory, my aunt sent it to me my youngest’s first Christmas and we read it on Christmas Eve every year, with “Twas the Night…”.
It tackles this very subject (True meaning of the holiday, what place all the other stories play, Santa, etc.) in the most beautifully simple way, and I am ever so grateful for it.
It’s called “The Christmas Lizard" and I give it my highest recommendation.
Buy it. Buy it now. ☺