Last month my publisher gave the green light to start work on The Same God? Reference and Identity in Jewish, Christian, and Muslim Scriptures. Yes, that old question of whether Muslims worship the same God as Christians, which surfaced again last year when Larycia Hawkins, an associate professor at Wheaton College, was suspended following her Facebook post citing Pope Francis's statement that Muslims and Christians worship the same God. Bill Vallicella has a good post about the question here, and see Beckwith’s discussion, as well as this by someone called ‘Tuggy’.
The first, and natural reaction, is that the Muslim and the Christian God cannot be the same, given the radically different conceptions that Muslims and Christians hold of the supreme being. Muslims believe that God is not triune, Christians believe that he is triune. Since being triune and not being triune are incompatible, it follows that no being could simultaneously instantiate the Muslim and the Christian conceptions, and so, given that there can be only one supreme being, it seems to follow that Muslims and Christians do not worship the same God. On this view, either the Christian or the Muslim is an idolater: one or the other entertains a conception of something that does not exist, but that which does not exist cannot be a genuine object of worship. But not so fast! As Christopher Howse pointed out here, the fact that you think others are mistaken in their description of someone's characteristics does not mean that they are referring to a different person.
Someone, for example, might call Spartacus a "freedom fighter" and someone else call him a "murderous rebel", but they are talking about the same man.On this view, either the Christian or the Muslim is a heretic, by claiming that God has attributes which are contrary to the orthodox view. John of Damascus says:
There are many other extraordinary and quite ridiculous things in this book [Quran] which he [Muhammad] boasts was sent down to him from God. But when we ask: ‘And who is there to testify that God gave him the book? And which of the prophets foretold that such a prophet would rise up?’—they are at a loss.’ ‘Moreover, they call us Hetaeriasts, or Associators, because, they say, we introduce an associate with God by declaring Christ to the Son of God and God.’ ‘by avoiding the introduction of an associate with God you have mutilated Him. It would be far better for you to say that He has an associate than to mutilate Him, as if you were dealing with a stone or a piece of wood or some other inanimate object. Thus, you speak untruly when you call us Hetaeriasts; we retort by calling you Mutilators of God.’John is clearly referring to God throughout. Second, he is also stating what Muhammad says via indirect quotation: ‘which he [Muhammad] boasts was sent down to him from God’. Thus he concedes that the being that Muhammad is boasting about is identical to the being that he worships. And so it is heresy, not idolatry. Muhammad denies there is an ‘associate’ of the very same being that John worships. Muhammad does not deny the existence of Jesus, but he does deny the relationship between Jesus and God claimed by orthodox Christians. But it is still more difficult. Howse claims that when someone calls Spartacus a "freedom fighter" and someone else calls him a "murderous rebel", they are both talking about the same man. This begs the question. What relation is invoked by calling someone a name? How do we talk about that person? Well, we use a proper name like ‘Spartacus’, but how does a proper name enable us to do this? Does it embed a description like ‘Thracian gladiator who led an uprising against the Romans’? If so, names that embed contrary descriptions like ‘triune’ and ‘not triune’ cannot possible refer to the same being, and so we are back to the first position. The question is one of idolatry not heresy. If, on the other hand, proper names do not embed descriptions, if they simply refer to their bearers, then they must refer to an existing bearer. Hence (a) God necessarily exists, because I am able to refer to him in saying ‘God exists’ and (b) it must be possible to determine from the meaning of ‘God’ and the meaning of ‘Allah’ alone, whether they are the same being or not. If I know the meaning of an English word and an Arabic word, I must be able to say whether one translates the other or not.
Can we understand a proposition in which two names occur without knowing whether their meaning is the same or different? Suppose I know the meaning of an English word and of a German word that means the same: then it is impossible for me to be unaware that they do mean the same; I must be capable of translating each into the other. (Wittgenstein, Tractatus Logico-Philosophicus 4.243)Neither position seems tenable. More later, but as Vallicella says, there is no easy answer to the question. ‘It depends on the resolution of intricate questions in the philosophy of language’.