Can muslims say merry christmas to christians or others that celebrate christmas?

Religiously speaking, I don't know.

It's two words put together to say something nice.

Sarah

Why would they, it is not a religioius holiday to them. They would not say it any more than a athist or a jew would need to say it.

If for example they did not practice their faith strongly and were more into, the myth side of things, santa claus and presents, like too many people, including christians who put no real meaning into the holiday, I guess they would.