And yes, I basically am serious.
And without reading the posts, I am SURE that someone drags out the fact that the English capital X looks like the first letter in the Greek word Christos. This is indisputable .
Equally indisputable is the fact that, if 1 in 1000 who actually write XMas is even dimly aware of that fact... then I'm Bill Clinton.
The question of whether most people writing Xmas are aware of what it means has no bearing whatsoever on the question of why it came to be used in the first place.
The use of X to denote Christ throughout Christendom since the earliest times is indisputable, so what possible reason is there to think otherwise in this one instance?