I was always told that the Xmas thing (and presumably xtal) is because Jesus died on a cross and a letter X is also a cross. I don't know if this is true though.
It is the nature of human beings to associate things they
believe in in order to make sense of the reality
and their lives, more myth than facts. Take for instance the invention of the transistor which some attribute to the "generousity" of aliens
truth or myth it's much more then the eye can see. How about US president meeting with aliens to strike a deal of maintaining the power status quo and the famous Roswell incident, are we really unique in this universe.Look out for men in black.