This text quite plainly says not only that Muslims adore the one true God, but that the plan of salvation includes them. The Catechism also says that those who have never professed explicit faith in Christ can be saved in virtue of their moral striving (no. 847). These teachings, as I recall, come from the ecumenical documents of the Second Vatican Council. (Note that there is some tension in reconciling them with nos. 151 and 161 of the Catechism; if someone can reconcile these, please e-mail me; I suspect the solution has to do with implicit belief, being an ‘anonymous Christian’.)
At any rate, the orthodox tradition of the church throughout history has been clear in stating that Muslims (and other non-Christians) cannot be saved without joining the church. The Roman rejection of this ancient article of faith is, to me at least, a very powerful reason for failing to become Catholic. Sadly, many people become Catholic without considering these “tangential” issues which are commonly very powerful apologetic peices, and very often strike at the heart of our faith. I mean, how many Protestants have converted to Rome without even knowing about Rome’s position on the evangelized and comparing it to the tradition of earliest Christianity? The New Testament with the early tradition on the one hand, and Roman dogma, on the other, cannot be reconciled on this point; they are contradictory. The spirit of Catholicism, in struggling to keep the door of the kingdom of God open to unbelievers, is at root opposed to the spirit of the first Christians. (For a fairly involved survey of the NT claims on the reprobation of the unevangelized, see esp. John Piper, Let the Nations Be Glad! The Supremacy of God in Missions.)
I wished to say that in very strong terms to distance myself from the Roman doctrine. At the same time, though, I do think a case can be made for saying that Muslims and Christians serve the same God. My case for this is primarily exegetical: in Acts 17, Paul quotes “some of your own [pagan Greek] poets” as saying that “we are all his [God’s] offspring.” Paul is quoting Greek writers like Aratus. The interesting thing is this: in the passage Paul quotes, Aratus is speaking about Zeus, not Yahweh. Yet Paul identified the reference of Aratus’ words with his own God of the Jews and Christians. This is truly remarkable. And if Paul can say the Greeks who spoke of Zeus were really speaking of Yahweh, what is to stop us from saying a Muslim speaking about Allah is speaking about Yahweh?
The conclusion of all of this would seem to be that Christians and Muslims may perhaps serve the same God–that is, the same all-powerful, all-knowing being. But it would seem that Muslims attribute to this God properties that he does not have (e.g., non-trinitarian properties).
It seems to me that pluralists, who make much of the fact that the referent of all religious devotion is the same, do not appreciate a fundamental Christian doctrine, namely, that even if we do worship the same being, this is not sufficient for salvation. God has very strict requirements concerning proper worship; to worship him wrongly is to incur death. This is why, after saying to the Athenians, “what you worship in ignorance, this I proclaim to you,” Paul adds that, “God has [now] commanded all men to repent.”
Please e-mail me with any comments or questions.