I was in a conversation yesterday in which someone asserted that he did not believe in the devil. Even though the Church clearly teaches the existence of Satan and the other fallen angels, (see Catechism of the Catholic Church, 391 and following) I think it's not unusual for us Catholics to see such doctrine as imaginary.
I have mixed feelings about this. Certainly we ought to believe in the devil and the fallen angels, not only because it is an article of the faith, but because it is the devil's will that we don't. On the other hand, our concepts of faith and belief are so fragile in our time that perhaps sometimes we're better off not believing in the devil, or at least not having any excuse to advert to his existence. Let me try to explain what I mean.
I think that most people believe in God in some fashion. People easily say that they believe or assent to the idea of a 'supreme being' or an 'intelligent designer' or some other human description of deity. What we fail to do is to believe God, that is to say assent to and believe what this God has said about himself through divine revelation. If God is indeed God, then his communication is primary by definition and demands our total and complete attention and response. Our failure at this, as individual Christians, as Church, and as humanity in general is what reveals our lack of genuine belief.
In fact, then, our society's manner of believing in God is often the way in which we ought to believe in the devil. We 'believe in God' but we do not always 'believe God.' Likewise, we should believe in the devil, but not believe him. For everything the devil says is a lie. Even when it contains something like the truth, is is framed in such a way to mislead us and introduce further misery into the world. Therefore I think the devil rejoices somewhat in the civil faith that posits supreme beings and intelligent designers, for such a faith allows us to think of ourselves as theists while simultaneously absolving us of the duty of religion. It gets us to the old assertion, 'I'm spiritual, but not religious.' That is to say that I am comforted and supported somewhat by something transcendent, spiritual, or supernatural, but am not challenged in any difficult way by what it demands. I am comforted but not converted.
On the other hand, my experience in the care of souls has convinced me that it can sometimes be quite unhelpful to give attention or thought to the devil. Classically, our temptations and difficulties arise from three sources: the world, the flesh, and the devil. My experience leads me to believe that diabolical temptations are the rarest. Indeed, I think it is one of the devil's standard victories to have us blame our worldly and fleshly temptations on him in such a way as to avoid our own responsibility to them. E.g. 'the devil made me do it.' No. I did it. Yes, my thoughts are confused and my will is wounded, but most of my temptations are from the occasions of sin that arise through my own fault, distraction, and spiritual torpor. So many times it turns out that blaming the devil for our temptations and sins is actually a distraction in itself and thus an oblique victory for the devil. This is not to say that there aren't actual diabolical temptations, but I think that they are rare. We are very good at displacing the source of our troubles when it comes to our spiritual life. 'Father, my husband has a drinking problem so I need you to put holy water on the house.' 'The brothers in this community keep me from having the prayer life I want.' 'How can someone be chaste in this culture.' There is no end to such examples.
So let's believe in the devil, but not believe him. Let us be quick to acknowledge his danger and influence, but recognize as a temptation the ease of allowing it to relieve us of our responsibility for ourselves.