The X in Xmas is a Greek letter, and the objection is younger than the spelling

This is less a set of instructions about the abbreviation Xmas than an argument, and it is worth saying so at the start.

What the letter actually is

The Greek word rendered in English as Christ begins with the letter chi, which is written in a form identical to a Latin X. Scribes working in Greek and later in Latin routinely abbreviated sacred names, partly for reverence and partly to save expensive writing material.

Those abbreviations were a recognised system rather than laziness, and readers of the period understood them immediately. The practice is visible in surviving manuscripts and inscriptions, where the same shortening is used consistently across many texts. So the X is not a substitution for the name at all; it is the first letter of the name in its original alphabet.

How old the abbreviation is

Forms using the Greek initial appear in English writing many centuries ago, long before printing and very long before commercial Christmas. Related abbreviations were used for other words built on the same root, including the adjective and the derived personal names.

The convention survived into printed English and was entirely uncontroversial among the people most concerned with religious writing. Some early printed material uses it precisely because compositors were short of space, which is the same practical logic as the scribes. A shortening used by monks copying scripture is a strange candidate for a modern accusation of irreverence.

Where the objection came from

Complaints about the spelling grew in the twentieth century alongside broader anxiety about the commercialisation of the holiday. In that context the X read as a blank, a crossing out, or a deliberate removal, because most readers no longer knew any Greek. The loss of classical education in general schooling removed the knowledge that made the abbreviation legible.

Where the story actually begins, once the letter looked like an erasure rather than an initial, the objection followed naturally and reasonably. This is a misunderstanding produced by a change in what readers know rather than by anything the writers did.

The wider pattern of sacred abbreviation

Several traditions have systems for shortening or avoiding the full writing of holy names, often for reasons of respect. Manuscript conventions across medieval Europe used a large number of standard contractions, marked with lines above the letters. Those marks disappeared as printing standardised spelling, leaving a handful of abbreviations stranded without their original signals.

The ampersand and several currency symbols have similar histories as compressed handwriting that outlived its explanation.

Symbols tend to survive long after the knowledge that made them readable has gone, which is how they become mysterious.

What the argument is actually about

Most people objecting to the spelling are not making a claim about orthography but about commercial pressure on a religious festival. That underlying concern is a real one and does not depend on the etymology being what they think it is.

Checked against the record, correcting the etymology settles the spelling question and leaves the substantive disagreement exactly where it was. It is worth separating the two, because winning a point about Greek letters does not answer anyone's objection to the shopping. Arguments about symbols are usually arguments about something else, and the symbol is the part that gets discussed.

How to use it

In formal writing the full spelling is safer, since a reader who objects will object regardless of the history. In informal writing the abbreviation is ancient, respectable and entirely defensible if anyone raises it. The pronunciation with the letter name is a modern development and is what irritates some people most.

Checked against the record, reading it aloud as the full word restores the original logic, since that is what the abbreviation always represented. Very few spelling controversies come with a manuscript record this clear, which makes this one unusually satisfying to settle.

The takeaway

The letter is not a crossing out. It is the name, written in the alphabet it was written in first.

Ask who gained from the claim being repeated. That usually explains the rest.