What it means and why some people don’t like it…
Spoiler: Xpofer means “Christopher”
Starting as early as the 3rd century A.D., Christian scribes regularly abbreviated often-recurring names of God. These abbreviations were known as nomina sacra. Here’s a great little paper that tells all about it.
If you’ve paid attention when visiting older churches or touring cathedrals, you’ve probably seen several: INRI, IHS, XP, ICXC, etc., some stylized into singular monograms.
The abbreviation of interest to us is obviously “Xp”. These are not the actual English letters X and P. They are the Greek letters Chi (X) and Rho (ρ), the first two letters in Χριστὸς, the Greek word for Christ. If you’re interested in the Greek, here’s the breakdown:
Χ (chi) – Sounds like “C”
ρ (rho) – Sounds like “R”
ι (iota) – Sounds like “I”
σ (sigma) – Sounds like “S”
τ (tau) – Sounds like “T”
ὸ (omicron) – Sounds like long “O”
ς (also a sigma) – Sounds like “S”
So Χριστὸς in Greek is pronounced “Cristos,” the Greek word for Christ.
So the English letters Xp (or sometimes just an X) are used for the Greek letters Χρ, and you end up with a church-created, church-endorsed, 1750-year-old abbreviation for Christ. This led to other derivative abbreviations: “Xtian” (or “Xian”) for Christian, and (wait for it) “Xmas” for Christmas. I only mention this because I grew up being told that anyone who dares write “Christmas” with an X is only seeking to remove the name of Christ. They clearly hated God. As it turns out, they are using a long-standing, church-approved abbreviation.
Starting in the middle ages, it became normal practice to abbreviate common first names on official documents. The most well known are “Geo” for George, “Chas” for Charles, and “Wm” for William. If you’re interested in more, this website claims to be the most exhaustive list available.
One shortened name that was derived from the old church abbreviations was Xpofer, which was literally “Christ-ofer”. This one wasn’t nearly as common as George, William, and Charles, but it was definitely well established. Why it fell out of common use I don’t know. If you Google “Xpofer” now, you’ll likely just end up with links to some old census records.