I don’t think so. The article calls him an Egyptian soldier, but he wrote in Greek, and was serving in the Roman army. 1800 years ago woul put this letter around the year 214 AD, well into the Christian era. He was apparently Greek and serving overseas..................
...and the Postal Service has only just delivered it. :-)
Rome did not become Christian until a century later. He believes in the gods but he does not feel confident the situation was going to improve. On the eastern frontier, things were tense with the barbarians menacing it.
Lots of Greeks in Egypt after Alexander. Cleopatra of the Ptolemys was the most famous.
A soldier’s lot hasn’t changed much down through the ages, does it?