ummm… it was a Z followed by a B 
I now use it in normal conversation… 
XMAS Hmmmmmm well Christ was not X for a start. Any chance of dropping the X ■■? That is offensive if you really care about the Mass of Christ. When did you last hear a Buddhist referring to his or her saviour as Buddy? Hmmmmm (Marje Simpson stylie) CHRISTMAS would be nicer …
Jesus was not an ‘x’ 
Many moons ago, my Dad joined theRoyal Navy, and in the joining process he was asked his religion. When he replied that he followed The Salvation Army, the blokes behind him in line sniggered. The N.C.O. on the desk rounded on the men that sniggered, and hissed ‘Don’t you EVER laugh at another mans’ faith!’
Enough said.