First of all, this post is not about whether Muslims or Christians have a correct understanding of 'God'; or about which religion represents the fullness of the truth. Neither is it some sort of "clash of the titans" in which I pit one 'God' against another to see which one wins out. It is, rather, my attempt at bringing clarity to an ongoing debate among Christians. I am, of course, referring to the question of whether or not Christians and Muslims believe in the same 'God'. This topic recently caught the attention of several major news agencies when Larycia Hawkins, a professor at Wheaton, pronounced that Christians and Muslims do, in fact, worship the same 'God' and further declared her intention to wear a hijab.
I have no desire to enter into the debate over whether or not Wheaton is justified in suspending professor Hawkins. Nor do I care to make a comment on her choice to wear a traditional Muslim head covering. What I am interested in, however, is whether or not her assertion is correct: Do Muslims and Christians believe in the same 'God'?
I shall argue they do . . . and they don't.
What Do You Mean by 'God'?
Before we can answer the question at hand, we must first define what we mean when we use the word 'God'. Broadly speaking, 'God' can be taken in two ways: (1) as referring to the divine nature in general, or (2) as referring to a specific deity (i.e., a particular manifestation of the divine nature) who has revealed him/her/itself in a particular time and place in history.
Considered in the first sense, the term 'God' refers to what Aristotle called the 'Unmoved Mover' or 'First Cause': a being that everything depends on for its existence and who can be, in the words of St. Paul: "understood and seen through the things he has made" (Romans 1:20). St. Maxamus the Confessor referred to this same divinity as that which has ontological priority:
“Everything that derives its existence from participation in some other reality presupposes the ontological priority of that other reality. Thus it is clear that the divine Cause of created beings - which derive their existence from participation in that Cause -- is incomparably superior to all such beings in every way, since by nature its existence is prior to theirs and they presuppose its ontological priority” (Maximus, 1990 p165).
In like manner, St. Augustine referred to 'God' as the 'ultimate ground of all being' or 'ultimate reality'. These great thinkers are representative of a much larger philosophical and theological tradition (which includes Jewish, Christian, and Muslim philosophers) known as Classical Theism (CT).
Proponents of CT not only contend 'God' is the ultimate ground of being, and in fact the greatest of all conceivable beings, but also share a common view on the basic attributes or properties of 'God'. Traditionally, this includes the idea that 'God' is immutable, uncircumscribable, incorporeal, metaphysically simple, and unknowable (in terms of directly apprehending what he is). Furthermore, proponents of CT all share the common view that knowledge of the divine nature (in so far as we are capable) can be obtained through a posteriori reasoning and is accessible to anyone with an open mind.
Considered in the second sense, however, 'God' refers to a specific deity. In other words, it points to a particular manifestation (or, alleged manifestation) of the divine nature who has revealed him/her/itself in a special way in history. Major examples of this would include Yahweh, who revealed Himself to Moses on Mount Sinai, or Allah who revealed His will to the prophet Muhammad in a cave on Jabal an-Nour, and Jesus Christ who revealed the Trinitarian nature of God through His baptism in the Jordan river (Cf. Mark 1:9-11).
To be clear, I'm not claiming all of the divine revelations recorded in all of the world's religions are merely different manifestations of the same divine nature. That is, I'm not espousing some form of universalism. I am simply making a distinction between two common ways people--especially theologians and philosophers--use the term 'God': one way uses the term to refer to the divine nature (as it is conceived by CT) and the other way uses the term to refer to a specific, more personal, manifestation of the divine nature in history.
Muslims and Christians Believe in the Same God
Now that we've defined our terms, let's examine the proposition:
(a) Muslims and Christians believe in the same 'God'.
If we interpret the word 'God' in proposition (a) in the first way--as referring more generally to the divine nature (i.e., the First Cause of all things, the ultimate ground of all being, which has ontological priority, and shares the list of divine attributes discussed above)--then, clearly (a) is true. For, on a whole, proponents of CT--be they Christian or Muslim--share the very same general conception of the divine nature. In which case, we can interpret (a) as:
(a)' Muslims and Christians believe in the same 'divine nature'.
Likewise, if we interpret the word 'God' in proposition (a) the second way--as referring to a particular manifestation of the divine nature--we might also coherently affirm the truth of (a). For example, Muslims believe the Prophet Muhammad is one (albeit, the ultimate one) in a long line of prophets Allah has revealed Himself to in history. Hence, they identify the 'God' who revealed Himself to Abraham and to Moses (whom Christians believe in) as being the very same 'God' who revealed Himself to Muhammad in the cave Hira. While they argue the Old Testament record of these divine revelations has been distorted, and that the fullness of the truth is only preserved in the Quran, they still identify Yahweh with Allah. In other words, they are making an 'is' of identity claim: 'Yahway' = 'Allah'.
Taken in this way, (a) could be interpreted as:
(a)* Muslims and Christians believe in the same manifestation of the divine nature (i.e., the same divine being who revealed Himself to Abraham and Moses).
Muslims and Christians Do Not Believe in the Same God
Equally, however, we can argue (a) is false. For if we interpret 'God' in proposition (a) in the second way, but factor in the witness of the New Testament, we find there are certain features of God's nature Christ revealed that are antithetical to the nature of Allah as revealed in the Quran. Namely, Jesus revealed the Trinitarian nature of 'God' (Cf. Mark 1:9-11; Luke 3:21-22; John 8;58). Accordingly, Christians affirm 'God' is not one single hypostasis but tri-hypostatic: i.e., that the divinity exists as three distinct persons: the Father, the Son, and the Holy Spirit. Allah, on the other hand, is said to be one single hypostasis. The radical difference between these two alleged manifestations is significant. For, given what we've just said, proposition (a) would essentially mean:
(b) Muslims and Christians believe in one 'God' who exist's as three persons and in one 'God' who exists as one person.
Clearly, however, this statement is false. Not only is it a contradiction, but both conjuncts are false: Muslims ardently affirm 'God' is a single person and Christians ardently deny 'God' is a single person.
As you can see, the question of whether or not Christians and Muslims believe in the same 'God' is rather tricky. If professor Hawkins intended to communicate the fact that, traditionally, Christians and Muslims have shared the same basic conception of the divine nature (as conceived by CT) then her assertion is correct. Furthermore, if her point is that Christians and Muslims both claim to believe in the 'God' of the Old Testament--the 'God' of Abraham and Moses--then she is also correct.
Anything more than this, however, would be problematic. Christians believe in the Trinitarian nature of 'God' as revealed by Jesus Christ (whom they believe to be the incarnate Word or Son of God). Furthermore, they identify the Holy Trinity with the 'God' who revealed Himself to Abraham, Moses, and all of the Old Testament saints. In fact, the doctrine of the Trinity and the Incarnation are arguably the most important doctrines of all the Christian doctrines. Yet, Muslims, following the teaching of the Quran, adamantly deny these two doctrines; according to them, Allah is one single hypostasis.
Given this, we can hardly claim, with any amount of consistency, that Christians and Muslims truly believe in and worship the same 'God'.