Bible Bedtime 2: The Nativity by Martin Coleman
Children's book explaining the true meaning of Christmas, which I got given as a freebie and "test read" to see if it was religiously sound enough to give to friends who have children.
It tells the story of the Nativity in a simple way that is easy enough for kids to understand, without being too heavy. I quite liked the use of humour in it (it suggests that the shepherds amused themselves by playing i-spy, and suggests that the emperor created the census because he was bored.
It was only later that it occurred to me that the book doesn't exactly spell out the fact that Jesus is the son of God, though it does mention that He will save the world - I'm sure all of that stuff wouldn't be considered too difficult for Children to comprehend.