I think you are wrong. "X" is a completely appropriate way to shorten the word and it has nothing to do with taking Christ out of Christmas.
According to whom? Not me, not that my thought counts for anything. As far as I am concerned it absolutely removes Christ from Christmas.
Just because everyone knows what xmas stands for, doesn't make it right or apporpriate. Like people pronouncing often (the t is silent) as of-TIN in a vain attempt to sound more intelligent.