I've just read this statement by the author Alan Moore:
"Largely, this was because Rome relied on foreign troops - on cavalry from Egypt, for example - to defend the Empire . . . . Foreign soldiers were originally happy to enlist, since Rome at that point took a pagan and syncretic standpoint that allowed recruits to worship their own gods while they were off in northern Europe . . . . Once the Empire had been Christianized, however, that was not an option. Rome's new Christian leaders decided it was their way or the stairway, and so consequently, off in distant lands, recruitment figures plummeted."
My question: Is this correct? Did the Romans hinder recruitment by pressing Christianity on non-Christian recruits?
(I'm well aware of foreign or Roman troops worshipping their non-Christian gods in pre-Germany, there's an Isis-temple here in Mainz.)
Text is from "25,000 Years of Erotic Freedom"
Looking through secondary sources on Late Roman armies, I am not sure this statement by Moore is sustainable.
Huns, Goths of various kinds, etc., are all use as foederati through the 4th and into the 5th century. Furthermore, there was recruitment into regular ranks of foreigners, into the auxilia rather than the legions.
Wikipedia is actually well sourced on the topic, and a good place to start. You would do well to note the argument that the 4th century army, under the growing Christianisation of the Empire, was more dependent on foreigner recruitment than the 1st/2nd century argument.
The main secondary sources on the issue to look at include Hugh Elton Warfare in Roman Europe, AD 350-425 1996, and A.H.M Jones Later Roman Empire, 1964.
In fact, looking through Averil Cameron's book The Later Roman Empire, the general assumption goes the other way. pp148ff basically assume that there was, compared to earlier eras, significant barbarian constituency within the military, and the pages before this discuss the problem of using various tribes as foederati in return for lands but failing to properly integrate them into the Empire.
In all this there is little to no evidence that recruitment fell, let alone that there was a policy of imposing Christianity onto recruits.