I agree with the sentiment, but do remember, there are American soldiers of multiple religions.
I think the people in the service appreciate the cards and care packages, even outside of the holidays. I don't remember what the organization was that offered the care baskets, but I remember that there was a group where you could buy a care basket and it would be sent to a soldier either stationed or recovering. I always thought that was a pretty neat thing. It had a card, chocolates, etc, and was certain to brighten someone's day.
If anyone remembers that link, perhaps they could put it here?
"Neca eos omnes. Deus suos agnoscet!"
(Kill them all. God will know his own.)
-- Arnaud-Armaury, the Albigensian Crusade