It isn't true, of course, that Obama ever banned using the word 'Christmas,' but if it makes the far right fundies happy to believe that he did and that Trump has saved Jesus from the Godless libtards... well ... ignorance is in fact bliss.
It is pretty much in keeping with the far right idea that God has anointed Trump, quite literally, to serve as a sort of Cyrus III. They are perverting Isaiah Chapter 45 to 'prove' this.
Laurie Roth, a far, far out right-wing 'Christian' columnist, has said so.
Roth draws her theological insight from Lance Wallnau, who has written several articles on the Second Coming (abridged version).
Meanwhile, as to Obama 'banning' the use of the word 'Christmas,' take a look at this article on RightWing News:
Obama bans the word 'Christmas'
Yet in the article, we see that even these RabidRighties admit their headline is a phony; that Obama said no such thing.
Here is what they do say:
Even if it is just ‘recommended’ to military personnel to not say Christmas, that in fact acts as an order.
Really? Apparently the Marines and the Army did not get the memo:
MCAS Cherry Point Christmas activities
Fort Carson Christmas activities
Of course, this is all due to Trump's recent election. The Marines and the Army are no longer cowering in fear ...
Never mind they've been doing this the entire eight years of the Big O's administration.