It is well noted in the study of Hagiography, as well as general Patristic studies, that for earlier Christians the desert was recognized as the domain of the Devil; where demons reside. For instance, consider the conviction of the desert fathers, and more explicitly the example of St. Anthony the Great as it exists in the Christian imagination (See paintings of the temptation of St. Anthony, for example). Today, we might recognize this belief to be primitive and difficult to reconcile with modern temperament, even theologically. However, I want to suggest simple way to understand this commitment which will neither violate modern theological temperament (at least, not significantly) nor betray the insight of the Fathers and the assumption of the ancients.
Consider by analogy that Christ ascended into heaven, while ascending towards the sky and away from the earth. Obviously an ancient assumption was that heaven was in, above or ‘towards’ the sky (thus the word is often used interchangeably for paradise and sky). We may no longer believe that heaven is ‘in the sky’, and yet we retain the ancient conviction that heaven is, being not a particular place at all, symbolically represented by the sky. This is a point on which we would not find much disagreement from the ancient Christians and Jews who presumed that heaven was in some sense present, maybe omni-present. Moreover, the logic employed is one of a ‘cosmic liturgy’ according to which the things in the world are intended to symbolize greater realities for us – thus the sky is intended to be a symbol of heaven, just as under-ground is naturally a symbol of death and darkness. This explains why Christ ascended upwards instead of, say, just disappearing or else sinking down into the earth. I recall Peter Kreeft once saying something to the effect of “we’d have a radically different religion [if we imagined heaven to be symbolized best by the ground beneath our feet instead of the sky above our heads and out of our reach].” Thus it was thoroughly appropriate for Christ to ascend towards the sky, as God was there making use of the very symbol he had intended to represent that very thing: heaven. Thus God intended that we recognize in certain images of things in the world an analogy of a kind.
Now, this notion of a cosmic liturgy can do more work than is immediately realized (imagine it’s application to Genesis, for instance). However, I think it can also legitimately be used here, and the argument looks rather similar. The desert is obviously a place of dejection and despair, or at least one of ‘being without’ community/communion. One was sent out into the desert when one had no choice but to flee and abandon their own people (for instance because of a crime they committed). Thus, the desert represents prospective death, the antithesis of promise or paradise. This makes it the most suitable natural symbol of a place where devils lie in wait to devour men. There is perhaps even something to be said for the Jewish image of Hell as ‘Gehinnom’ which is the word Jesus constantly uses in the Gospels. In any case, one can salvage the insight of the ancients without sacrificing credulity, I think, by appealing to this liturgical paradigm of analogy.