From the Second College Edition of the American Heritage Dictionary:
"X, the Greek letter chi, abbreviation of Khristos, Christ"
It's humorous to me to see religious folk get bent out of shape when they don't even know what they're talking about. "Xmas" isn't taking "Christ" out of anything. The abbreviation has been used for hundreds of years. It still literally means "Christ-mas." Just like your little fish symbols you have on the back of your cars mean "Christ".
An unexamined life isn't worth living.