Is it fair to make the only Christian work on Christmas?

The point being just that, yeah, there are some jobs that need people present all the time. Sad but true. If you feel you are being singled out in some unjust way, discussing it with management or HR or whomever seems appropriate. If you just somehow got picked at random, it would be reasonable to ask to switch -- maybe you can volunteer for the next holiday -- but a lot of people expect Christmas off, regardless of personal beliefs, so there might not be anyone willing to trade. :-)

Who? If you're in an on-call position then this is pretty typical.

Saying that i'm athiest myself so Christmas is more just a tradition for me, so having to work it is just annoying.

I'd personally prefer my employer to not track the religions of its employees and then feed that to whatever people and software they have doing scheduling.