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:

Get real. Don’t even post this garbage.
This is the result of racism and political hatred. This kind of lie makes me sick to my stomach.
Merry Christmas. Obama, may God have mercy on your soul!
He just declared war on Christianity
Merry Christmas everyone
Go to hell obama
Merry Christmas to all military personnel.
This can’t be true.
Our president is a fuquin count that’s why
http://www.snopes.com/obama-military-christmas-ban/