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:

Happy Holidays everybody!!!
Seems like more$#%&!@*propaganda…
MERRY CHRISTMAS!!!
I would say it anyway. That is an unlawfull order
This Is not true!
This isn’t even true! So quick to believe a lie!
Just like the right wing. The first thing I did was look this up because it sound right! You’re all idiots!
This is one stupid, petty, bath house gaybo.
Take a hike barry we’ll say Christmas anytime we want…
phuck Obummer
Any other person would be impeached by now! How does he get away with all this? Unreal!