The Obama administration has directed the military to not allow personnel to say “Christmas”, in spite of the holiday’s status as a federally-recognized holiday.
The reason given by armed forces officials is that not everyone celebrates Christmas and that out of respect for them, military members should refer to Christmas celebrations simply as “holiday”-themed festivities.
This prohibition comes in the context of a wider push for political correctness in society in general and the military in particular, as evidenced by the recent reprimanding of Navy Chaplain Wes Modder for simply discussing religion, as chaplains are wont to do, with military personnel.
See how servicemen have reacted to not being allowed to say Christmas at the link below:

this is an unlawful order.
Obama belongs in Kenya were he came from & get out of America The people that voted for Obama better pray because America & the world is going to need the the Lord to get out of the mess Obama has done to America.
Ignore.
When did our First Amendment Rights get taken away? Pretty soon you will be informed under Net Neutrality it’s illegal to post Merry Christmas on Facebook on a Public Post.
You should say Merry Christmas every other word!! Your people said its OK! Screw that idiot!
The only one who won’t be merry this Christmas is Obama because his rules will be almost over
Well said John Laidlaw, point on
Merry Christmas and go away Obama!! You don’t get to order me or mine on what we can and cant say
MERRY CHRISTMAS To all our Military
What an idiot