Xian is a Chinese word for an enlightened person
Abbreviation for the normal English word "Christian."

X-as-chi was associated with Christ long before X-as-cross could be, since the cross as a Christian symbol developed later. (The Greek letter Chi Χ stood for "Christ" in the ancient Greek acrostic ΙΧΘΥΣ ichthys.) While some see the spelling of Christmas as Xmas a threat, others see it as a way to honor the martyrs. The use of X as an abbreviation for "cross" in modern abbreviated writing (e.g. "Kings X" for "Kings Cross") may have reinforced this assumption.

In ancient Christian art χ and χρ are abbreviations for Christ's name. In many manuscripts of the New Testament and icons, X is an abbreviation for Christos, as is XC (the first and last letters in Greek, using the lunate sigma); compare IC for Jesus in Greek. The Oxford English Dictionary documents the use of this abbreviation back to 1551, 50 years before the first English colonists came to North America and 60 years before the King James Version of the Bible was completed. At the same time, Xian and Xianity were in frequent use as abbreviations of "Christian" and "Christianity"; and nowadays still are sometimes so used, but much less than "Xmas".