The Devil occupies a curiously ambiguous position in contemporary American spirituality. There are two main atmospheres. The distinction cuts across the important distinction between Protestant and Catholic Christians, and people of each sort can be found in nearly every denomination, if not every congregation.
One may, loosely, be called the minimalist school; it is far the larger of the two. Many who are (in this respect) minimalist doubt, or explicitly deny, that the Devil exists at all; or redefine it to the point that it means little more than the selfish impulses of mankind. Some others who are of this atmosphere, particularly evangelicals, admit the existence of the Devil as a personal being but pay little attention to the matter. The Devil, for them, is a being who does exist in principle, but cannot be expected to exercise any noteworthy influence upon the daily life of the Christian. Such views are often bolstered by the contention, not supported by Scripture or the historical consensus of the Church but popular nonetheless, that believers are immune to possession or indeed any form of diabolical attack because of the indwelling of the Holy Spirit.
The other might be called the apocalyptic perspective. It consists chiefly in charismatic Christians both Catholic and Protestant, Dispensationalists (a la Left Behind), and such Catholics as might be called 'rigorous.' These believe quite fervently in the Devil, and see his operations in many if not all areas of human life and society. Some of them are very happy to instruct the ignorant and admonish the sinner enthusiastically on such matters; and we may pray that their works of mercy commend them to God.
Some readers may be surprised that I have used liberal and conservative, respectively. This is intentional; the terms are not really applicable. The word liberal is properly a political rather than a theological term, and is therefore not specially suitable for discussions of Christian thought. A more accurate term for that theology called liberal would be Modernist; but, since Modernism has been condemned as a heresy, there are few who would take up such an appellation in the Catholic Church; and Modernist Protestants are many things, but being wedded to clear, fixed terminology is not one of those things. As for the fanaticism being conservative, that is a fantasy, projected by progressivism onto ignorance of the past. The degree to which orthodox theologians emphasize the reality and activities of devils varies and always has; some ages have been hysterical on the subject and others stuporous, or anything in between; and the attention paid to the diabolical by the Church has rarely corresponded to the rationalist's definition of what qualifies as a superstitious age.
The sort of attitude taken by informed and thoughtful Catholics has been -- with allowances for the emphasis of differing times and cultures -- that the Devil is not only personally real (of which more in a moment), but that devils are active in the spiritual lives of human beings; but that, nevertheless, most things which people attribute to the Devil are natural phenomena. This is not because the activity of evil spirits is intrinsically improbable, but just because people are excitable and prone to make mountains out of molehills.
The Doctrine of the Fallen Angels
The Catholic belief in devils is derived both from Scripture and from the unanimous testimony of the Church. It is dependent on the ancient Jewish-Christian belief in angels: these are free, intelligent, incorporeal beings who carry out the will of God. It has long been believed that there are nine varieties of angelic beings, of whom three do not concern us, while the other six are concerned in differing capacities with the material universe in general or with the human race in particular. Of these, some -- since they have free will and can therefore choose either to obey God or to rebel against Him -- chose to revolt against their Maker, thus becoming what we call devils or demons. In so doing, they became morally depraved; but their powers, which are in the nature of angels rather than being a reward for obedience, remained intact.
None of this should be confused with the dualist concept, popular among the Gnostic heretics of the early centuries of the Church and the high Middle Ages. Many ill-educated persons, Christian and otherwise, are under the impression that it is an article of the faith that the Devil, like God, is eternal, all-knowing, omnipotent, and as it were disinterested in his pursuit of evil. The Devil, in a dualist ideology, is the embodiment of evil as God is of all good.
This is not only unorthodox but literally impossible in Christian theology. Christianity regards God as the Maker of all things seen and unseen, and the Catholic is bound to regard existence as good in itself. C. S. Lewis disposed very neatly of this idea in his introduction to his invaluable book The Screwtape Letters; he there points out that no being could attain a perfect badness as God has perfect goodness; for once you had taken away every kind of good thing, including intelligence, will, and being itself, there would be nothing left to be bad with.
It is likewise worth pointing out that, though Catholics do believe that the Devil in fact brought about the Fall of Man by tempting us, this did not have to happen. Most if not all the evil in the world may be traceable, directly or indirectly, to his malice; but men are free also, and there is no particular reason why we should not have fallen all by ourselves, if the Devil had remained good or if his assault on our innocence had been unsuccessful.
The Satanic Verses
Now, down to brass tacks. The existence of the Devil in the abstract is all very well (or perhaps not), but what has it got to do with our lives as we live them?
Well, to begin with, there are the continually reiterated Scriptural warnings to beware of him; they are in St. Paul:
See to it that no one takes you captive by philosophy and empty deceit, according to human tradition, according to the elemental spirits of the world, and not according to Christ. (Col. 2.8)
What do I imply then? That food offered to idols is anything, or that an idol is anything? No, I imply that what pagans sacrifice they offer to demons and not to God. I do not want you to be participants with demons. (I Cor. 10.19-20)
And you were dead in trespasses and sins in which you once walked, following the course of this world, following the prince of the power of the air, the spirit that is now at work in the sons of disobedience ... (Eph. 2.1-2)
Be sober-minded; be watchful. Your adversary the devil prowls around like a roaring lion, seeking someone to devour. Resist him, solid in your faith, knowing that the same kinds of suffering are being experienced by your brotherhood throughout the world. (I Pet. 5.8-9)
Submit yourselves therefore to God. Resist the devil, and he will flee from you. (Jas. 4.7)
And certainly St. John:
Whoever makes a practice of sinning is of the devil, for the devil has been sinning from the beginning. The reason the Son of God appeared was to destroy the works of the devil. ... By this it is evident who are the children of God and who are the children of the devil: whoever does not practice righteousness is not of God, nor is the one who does not love his brother. (I John 3.8, 10)
Nor can we reasonably suppose that these were superstitions indulged by the Apostles, which their Master took no part in. Quite apart from His character as an exorcist -- up to and including discourses on the habits of devils (cf. Matt. 12.22-45) -- He speaks freely in the Gospels about the Devil as the animating power behind evil in this world:
Jesus said to them, 'If God were your Father, you would love Me, for I came from God and I am here. ... You are of your father the devil, and your will is to do your father's desires. He was a murderer from the beginning, and has nothing to do with the truth, because there is no truth in him. When he lies, he speaks out of his own character, for he is a liar and the father of lies.' (John 8.42, 44-45)
The New Testament both presupposes (in speaking of exorcisms) and directly teaches the existence, malevolence, and power of demons. But what does that mean -- especially if we do not need to suppose a diabolical origin for every human evil?
The key is to be found in a passing remark of St. Paul's: he speaks of those trying to discredit his ministry, calling them false apostles, and adding, And no wonder, for Satan disguises himself as an angel of light. As the Flesh signifies the temptations of individual human nature, and the World the temptations of the various established systems, so the Devil signifies not simply one depraved seraph, but the general category of depraved spirituality. It is more than natural that we should be warned of his power so constantly, and in such severe terms, as the Apostles insisted on penning. For a depraved spirituality, which the devil and his angels are specially concerned to produce, is obviously a danger for anyone embarking on the spiritual life.
Such transcendental evil may ordinarily take one of three forms.
The Devil In the Details
There is, first, spiritual predation. This encompasses everything from temptation to full-blown possession, and makes better movies than the other two kinds.
On the whole, the predatory activities of the Devil are comparatively straightforward in this category: in temptation, he flatters and frightens in order to push us into sins, and then takes a malefic pleasure in accusing us thereafter. In obsession, a step deeper than temptation, he takes advantage of a pattern of sin into which he has trained a person, and uses it as a foothold within his personality, from which he tries to expand his territory. If he succeeds in tricking, cajoling or terrifying his victim into consenting, he may then move on into possession, in which he takes command of the person's body at will. This last requires an exorcism to be fully dealt with.
With most people, naturally, things do not go beyond temptation and similar forms of exterior harassment -- or, at most, obsession. Possession is rare, though not perhaps so rare as it was a hundred years ago; and this is in large part because of the second main form of spiritual evil.
This second form is spiritual error. This encompasses all manner of false beliefs, and the channels for invasive diabolical activities that such beliefs open. Everything from heresy to atheism to false religions can constitute spiritual error.
However, certain distinctions must be made. Not every incorrect belief has its origin with an evil spirit, or even that they find all false beliefs equally easy to manipulate. An untrue belief held merely by mistake, for instance, will not prove very fertile soil for the devilish weed; especially if the person who holds it is intellectually responsible, in which case the error will very likely be corrected. Nor does it mean that all or most principles of non-Catholic faiths are of diabolical origin. The Second Vatican Council's statement on the relationship of the Church to other religious traditions, Nostra Aetate, went out of its way to say that good and holy elements exist in the higher religions of the Orient -- even more so in Judaism and Islam -- and these good elements are not to be rejected.
What is necessary for a false belief to be a spiritual error in this sense is that there must be a spiritual agency of deceit operating within it. Some religions may have originated in this way, or incorporated such elements in themselves -- for example, through divination, inviting powers into human minds and thus opening them to demonic influences. The foothold of a devil in a specific person, exacerbating his desires not to see this or that truth and clouding his mind, would also qualify.
Spiritual error differs from spiritual predation in that it is directed toward a diffusion of falsehood, rather than tearing down one person -- it is the tilling of the soil, whereas evil spirit preying on an individual is comparable to a specific weed. Each furthers the other, but neither is necessary to the existence of the other.
Both are different from the last and worst form, which may be called false holiness. This is what the Bible calls hypocrisy; but the word hypocrisy has been rather worn down from overuse, and now includes things as simple as human failings out of weakness. Dr. Johnson's maxim should be kept in mind: precept may be very sincere where practice is very imperfect. Indeed, that seems to be what St. Paul is going on about in the second half of Romans 7. Mere failure to live up to one's convictions is not properly called hypocrisy, but simply sin.
What distinguishes false holiness from human weakness is a terrible sincerity in the person afflicted with it. False holiness need not be supported by heresy, or even moral inadequacy. Christ's attitude to the Pharisees is much to the purpose here, if only we will remember what it was. For it is noticeable that Jesus Christ and the Pharisees had a very substantial agreement on matters doctrinal. Nor was their practice, in His eyes, always reprehensible. Their study of the Scriptures was admirable in itself; their care for ritual purity may have gone beyond the Law, but it did not fall short of it, which is more than could be said for some Jews in Galilee or Samaria; and, while it may not have been in debilitating proportions, they did give to the poor. False holiness is often arrayed not only with doctrinal accuracy, but even with impressive personal virtue -- as was said of the puritanical nuns of Port Royal in seventeenth-century France by the local archbishop, "as pure as angels and as proud as devils."
Merely to say pride, however, is not informative. The distinction between false and true holiness lies in the motive behind it. T. S. Eliot laid his finger on it in his play, Murder In the Cathedral, in which St. Thomas a Becket is tempted to become a martyr for his own religious glory rather than for God: The last temptation is the greatest treason: To do the right deed for the wrong reason. A person under the power of false holiness may easily -- in fact, will probably -- be chaste, generous, truthful, wise, patient, just, brave; even humble after a fashion. It is deep inside the heart that the deadly poison has corroded him. It is there that, in truth, he cultivates these virtues, fights temptations, scorns the World, and even perhaps fights spiritual error -- for himself.
And there the devil sits, laughing without mirth.
Get Thee Behind Me
How, then, is the Devil to be fought? There is absolutely nothing we can do of ourselves. Our sole recourse is to give ourselves up to God, continually: through prayer, through Scripture, through the sacraments (particularly Confession and the Eucharist), and through sound spiritual direction (a principle neglected all too often). It is in these things that the Holy Spirit works. Prayer, so as to breathe the Holy Spirit, to be in continual, intentional contact with Him to the best of our ability. Scripture, to know what God says in general, and thus be better equipped to recognize His specific intimations to us. The sacraments, because in them God literally meets us; Confession, where He meets us with His forgiveness and healing, and the Eucharist, where He meets us with Himself. Spiritual direction, because we cannot dispense with the mentorship of someone who knows God and knows people, and knows how to bring people close to God -- the Pope himself doesn't go without one. (St. Teresa of Avila said dryly that he who is his own spiritual director has the devil for his spiritual director.)
And how are we to know that these very things are not done out of false holiness? Well -- we cannot manufacture true holiness; we can only ask for it. So ask for it.