All of which is to say that Catholics do not have the luxury of pretending that, when we need to oppose Muslims, we can suddenly pretend there is a Christian God and a Muslim God. There's just one (1) God and, insofar as people worship one God, he's the God they worship.
People may, of course, hold all sorts of false ideas about him. They can do all sorts of evil and tell themselves that's what He wants. But that does not change the fact that there is just Him and nobody else occupying the Throne. And it also does not change the fact that representatives of a religious system which he did not inaugurate (such as Islam) can still see (and respond to and even reflect) rays of his light. ...
Now, Bin Laden and Hitler have killed their thousands and millions, but Satan has killed everybody who ever lived. He is the author of death, the deceiver, arch-fiend and enemy of God who brought about the death of everybody who has ever died--not just concentration camp victims and Russian schoolkids, but *everybody*, including you, your loved ones, and the Son of God himself. He is as evil as it gets.
And yet, the Catholic tradition will not allow us to glorify him as "pure evil". It insists that insofar as Satan possesses such attributes as being, intelligence, will and power, something of God's goodness has a toehold in Satan's nature, if not in his choice. That's not an attempt to say that Satan is not so bad. Nor is it me talking. It's St. Thomas. Evil *cannot* totally corrupt good because evil depends on good. To totally corrupt what is good, it would be necessary to completely annihilate its being and that cannot be done. ...
Why does the Church do this? Not because it is trying to rehabilitate Satan or pretend that monsters who shoot children in the back mean well. It does not even do it to endorse some program of pacifism (Jesus certainly was no pacifist toward the Enemy of the Cosmos when he defeated him utterly on the cross). Rather, it is much more subtle than this: it is, paradoxically, to make sure that God retains every last drop of the glory due his Name and to make sure that *no* tribute is given to any creature that would seek to rob God of glory. Even the devil must bow the knee to God, however unwillingly, and acknowledge that he depends entirely on God for his existence. Similarly, what there is good in Islam is, ultimately, due to the fact that Islam preserves gifts given by Jesus Christ, the Son of the Living God. If a Christian, in his blind zeal to oppose Islam or some other syste [sic] (even Nazism), denies *any* goodness in a creature, he denies God glory.
This does indeed, have practical ramifications. "Blessed are the peacemakers" (and frequently cursed too) is one of them. For it means, for instance, that the awaited "Kill them all! God wills it!" that some Conservative Catholics seem to long to hear from the leaders of the Church will be a very long time coming. For the Church is bound to affirm what can be affirmed in common, not only with Islam, but with any human system of thought or religion. It is bound to look for the good that is being sought and to acknowledge it (no matter how sinfully that good is being sought). Bottom line: If even Satan can get his due from the Faith, then merely human systems of error are bound to get their fair shake too.
Have at it, meine Damen und Herren!