How many modern Christians do believe in ‘Satan’? Perhaps not many, even in those who do believe, we find that the usual modern conception of the demon is in fact rather "Manichaean" than Christian. The Satan our contemporaries refuse to face up to, or only with difficulty bring themselves to acknowledge, is a sort of Ahriman, a personal being, the horribly real incarnation of a Principle of Evil, the antithetical counterpart of the Principle of Good, which is God; so powerful that he is not merely the adversary but the rival of God : literally a counter-God, Antitheos.
We must realise that Satan - like the other demons, for though he is the most important he is still only one of them - is an angel. A rebel angel, a prevaricator, a fallen angel, indeed, but an angel still. He was created by God with and among the other celestial spirits, and even his fall and the disgrace it brought upon him could not take away the angelic nature that is the definition of his being.
For the theologian, demons come within the field of the treatise De Angelis. The doctrine is part of a most firmly established tradition. It has been clearly defined ever since the days of the second-century apologists. It is a doctrine that the Church has always and repeatedly stressed, every time a fresh threat of dualism (one of the perennial temptations of the human mind) has forced her to define the borderline of this section of her terrain. As early as the end of the second century St. Irenaeus was using it against the Gnostics; it reappeared in 563 at the Council of Braga to counter the Manichaean infiltrations of Priscillianism (DS 237); and in 1215 at the Fourth Lateran Council, against the Catharists (DS 428). There is no need to labour this point. It is a doctrine that everyone knows.
The reason why our contemporaries find the devil so hard to swallow is that they give scarcely any genuine thought to the angels. How can we fail to see that - except among theologians and truly spiritual souls - the place of the angels is fading out of our modern Christian thought and life? There is perhaps some vitality left in the devotion to the guardian angels, but that is looked on as a thing apart, quite disconnected from the rest of the theology of the angels. Think, for example, of the cult of St. Michael in the Middle Ages, witnessed to even now by monuments. The 29th of September is labelled by our liturgists as a First Class, but what does it mean to most Christians - instructed Christians - nowadays? This is certainly a result of the materialism that characterizes the culture of our age - or, to put it more precisely, to the over-exclusive value which is given to merely sensible experience, at the expense of all that relates to the intelligible, spiritual world within. Every Sunday Christians sing the Nicene Creed and claim to believe in a God who created "all things visible and invisible ". In practice they give no serious thought to the existence, the reality of the spiritual creatures of the invisible world. Here again we find part of the faith being cheerfully rejected in its implications.
On the contrary, for Catholics in the fourth century, the existence of angels both good and evil was not only the object of the most unwavering and explicit conviction but of concrete, every day, lived experience. It was as natural for them to say with the Psalmist, "In conspectu Angelorum psallam Tibi" as it was to admire the heroes of asceticism who went out to fight devils in the desert.
It was with the greatest matter-of-factness, the utmost realism, that the Christians of those days interpreted St. Paul's teaching: "We are not fighting with flesh and blood but with principalities, with powers, with the rulers of this world of darkness, with the wicked spirits spread through the air" (Eph. 5:22).
Non-substantiality of Evil
St. Augustine is often credited with the doctrine of the non-substantiality of evil. It is, however, such an essential part of Christian thought that it is even found in the doctrinal tradition of the Greek Church. We find it clearly if briefly formulated, quite independent of any connection with Augustinian thought, in St. Basil and St. Gregory of Nyssa. The first of these devoted a sermon to proving that God is not the author of evil, where he says, notably: "Do not imagine that evil has a real substance, hypostasis —perversity does not exist in the same way as a living thing. You can never have its substance, really there before your eyes, because evil is the privation of good."
Similarly Gregory of Nyssa in his famous Catechetical Discourse demonstrates that evil has not God as its author but is born within ourselves by the free choice of our will, when our soul in some way withdraws itself from good. Just as blindness is the privation of a natural activity, sight, the genesis of evil can only be understood as the absence, of good. Good is present in our nature. Evil, on the other hand, is non-existent, and only appears because of the withdrawal of good.' Good and evil are not each other's opposite in the order of substance, but in the way in which being is the opposite of non-being. Evil does not exist of itself, but is conceived as the absence of the better.
When we say that evil is not a substance, not a reality, when we say it is "a nothing ", we are not thereby denying its existence.. Evil has no place in the order of being. It belongs to non-being, which is not the same thing as nothingness.
The corrupt nature of the devil, or of man since the Fall, must be described as a mixture of being and nothingness; let us say that this nature is in some way flawed, riddled like a piece of dolomite or millstone - better still, like a sponge. Evil corresponds to the holes, the lacunae: it is emptiness, non-plenitude; the sponge only exists in virtue of the parts of itself which are, the solid material. Evil does not belong to being: it is a corruption of being, a defect, a disease, a disorder.
Satan, an angel, is the free being who first chose to move away from the Source of all being and towards the nothingness from which he had been drawn. He is indeed an ‘Fallen Angel’.
Condensed from "The Fallen Angel" by Henri-Irénée Marrou. in Satan, ed. by Père Bruno de Jesus-Marie, O.C.D (1952), p. 67-85 by Fr. Therasian Babu SSPX.