If it is private (people pay for services), then you can ask or poll parents, because they can voice their displeasure by disenrolling, but if you get any public money I wouldn't do religious oriented activities, even a poll in my opinion is not appropriate.
If everyone is Christian and says they want Santa and you're not, then how does it look if you say no? It looks horrible, people say they are tolerant, but many people are not and will make you pay. You're forced owing to circumstances to laugh and smile about thing you're not comfortable with.
As the kid who was different, I was forced to smile and play along with many things I was not comfortable with for "the greater good."