Most probably, Christian traditions, such as Christmas, will have been banned long ago due to their 'offensive' nature. In all likelihood, the only religion not outlawed by the 24th century will be Islam.
Firstly, the paranoid belief that Islam is somehow going to take over the world is fit for the same kind of person today that a hundred years ago would have been the crudest, foulest form of anti-Semite. Just in case you're curious at all about how this kind of rhetoric makes you look*.
Secondly, the paranoid belief that "Christian" traditions such as Christmas are particularly "offensive" to any significant number of people is an even less flattering form of silliness that basically announces to the world that you will swallow anything at all that Bill O'Reilly tells you. So, that's also something you might want to take into account.
Thirdly, the groups historically and presently known to
actually have a problem with Christmas have largely been hardcore Christians, such as the
Puritans who banned it in the mid-17th century; both because the holiday is scripturally unjustified and because it has traditionally encouraged un-spiritual revelry, frivolity and (today) conspicuous consumption. Which would suggest that any future in which Christmas were really banned would likely be one where militant Christianity was
more successful, not less so.
(* Talking about Christianity being "outlawed" in favour of Islam is, aside from being woefully paranoid, pure bathos; not that an ideology that contemplates outlawing religion is impossible to imagine, but any such ideology would target Islam as much as anyone else if not moreso. And if you're projecting Islam's
current status as fastest-growing religion on a straight uninterrupted line into the future, you are being a silly goose. Demographic trends do not work that simply.)