A War of Gifts
At the Battle School, there is only one purpose, only one curriculum: the strategy and tactics of war. The children are drawn from all nations, all races, all religions. There is no room for cultural differences, no room for religious observances, and certainly no room for Santa Claus.

But the young warriors disagree. When one of them leaves a Sinterklaas Day gift in his best friend's shoe, that quiet act of rebellion becomes the first shot in a war of wills that the staff of the Battle School never bargained for.
Ender Wiggin (Fictitious character), Fiction, Ender Wiggin (Fictional character), Toleration, Science fiction
Orson Scott Card
Orson Scott Card is an American novelist, critic, public speaker, essayist and columnist. He writes in several genres but is known best for science fiction. His novel Ender's Game (1985) and its sequel Speaker for the Dead (1986) both won Hugo and Nebula Awards, making Card the only author to win both science fiction's top U.S. prizes in consecutive years.