Papyrus is expensive. Scripture is repetitive. The earliest Christian texts used a clever set of abbreviations to save space and time.
If you’re ever reading Christian scripture, you can be sure that certain words will crop up fairly frequently: Jesus, Christ, God, and so on. It makes perfect sense to abbreviate such words, because it means that you can copy the text faster and use less space on the page. These abbreviations are known as the nomina sacra.
The basic form of a nomen sacrum is to take the first letter of the word and the last letter of the word, and put a bar over the top to indicate the abbreviation. The Greek word for Lord, for example, is Κύριος. The abbreviation is ΚΣ (or, ΚΥ if it’s possessive).
(Side note 1: this is not the same as the chi rho, the so-called Christogram today seen mostly in the X in X-mas. It’s pretty similar, though.)
Reading ancient Christian scriptures, you needed to know a good number of these sacred abbreviations to make any sense of the text. And even the earliest New Testament scriptures use them. Interestingly enough, it wasn’t just a matter of convenience: the words abbreviated in this way were all religiously significant: God, spirit, saviour, Jerusalem… Words that came up a lot but that weren’t sacred (like “and”) didn’t get abbreviated.
(Side note 2: many other non-sacred abbreviations have been used by scribes, and we see the remnants of them today in forms like RIP and &, but that’s a larger topic.)
Knowing the nomina sacra can also help when viewing early Christian art. The picture above, for example, identifies Jesus Christ with only four letters.