Why Do We Call It "Xmas"?

Lots of people think that the X in Xmas is a secular watering down of the word Christ. You know, "we love to celebrate the holiday but don’t believe in Jesus," sort of thing. However, that's not the origin of the X.

The X actually comes from the Greek letter Chi, which is the first letter of ???????. And if that’s all Greek to you, ???????, of course, means Christ.