Do Muslims and Christians worship the same God? This is perhaps the most significant question that has emerged during the increased interest in Islam in the decade following 9/11. Theologian Miroslav Volf tackled this thorny question in his new book, Allah: A Christian Response. Volf’s answer to the question is a qualified yes. That is to say, while Muslims and Christians have different understanding of aspects of God’s nature and character, so do Christians and Jews and, for that matter, so do different kinds of Christians. If we say that Muslims and Christians do not worship the same God, Volf argues, we have to concede that Jews and Christians (and Arminians and Calvinists for that matter) do not worship the same God. While Volf’s argument has a certain appeal, when we dig a little deeper, we find that it is built on a rather shaky foundation.
What Is Monotheism?
Christianity, Islam, and Judaism are commonly known as the “three great monotheistic religions.” But this label may assume too much. The word monotheism was not coined until the 17th century when Cambridge don Henry More used it to describe any view that held to one person (or principle) as God. The word was co-opted in the 18th and 19th centuries by OT critical scholars who were engaged in revising OT composition history. In the spirit of that age, they saw the history of religion on an evolutionary scale. As human religion developed, it progressed from pantheism to polytheism and finally to the “ethical monotheism” we see reflected in “Deutero-Isaiah,” his friend “Trito-Isaiah,” and other later prophets. This evolutionary process was a movement from the belief that all things are spiritual and divine, to the belief that only a few things are divine, and finally only one thing is divine.
Among other problems, this notion of religious history creates the possibility of an abstract monotheism in which the only real tenet is the belief in a single divine being. Unfortunately, most people on the street probably understand “monotheism” in this way (if they understand it at all). But there is a fatal flaw with this abstract monotheism: nothing like it actually exists. Whenever we talk about “God” in the abstract, we must immediately move to the concrete. That is to say, just as we cannot say anything specific about an abstract person without immediately explaining which person, we cannot say anything of substance about God without explaining which God. So then, if we assume the three monotheistic faiths are talking about the same God, we are begging the question. Not everyone who uses the word monotheism means the same thing by God. It seems this kind of circular reasoning can lead Volf to claim that those who deny Muslims and Christians worship the same God must also deny that Jews and Christians worship the same God. But this line of thinking misses an important part of the picture.
Early Jewish and Christian Monotheism
In the Old Testament, we certainly find the idea that there is one God who created all things, rules over all things, and will judge all people. In Isaiah 44:6, God proclaims, “I am the first and I am the last; besides me there is no god.”
But elsewhere in the OT, we find that this one God is only known because he reveals himself to a people. Deuteronomy 4:35 says, “To you [God’s power in the Exodus] was shown, that you might know that the Lord is God; there is no other besides him.” The quintessential statement of monotheism in the Bible, the Shema of Deuteronomy 6:4, is also found in this context. “Hear, O Israel. The Lord our God, the Lord is one.” This revelation was directed to Israel alone. Throughout the OT, the knowledge and confession of the one God is the property of Israel and not the nations.
When we turn to the NT, we find this confession expanding to include the nations. In Romans 3:30, for example, Paul says that the one God is now the God of both Jews and Gentiles together. Through Christ, the revelation of the one God now extends to the nations. However, this knowledge is still based on God’s self-revelation. And while he previously spoke in many times and in many ways through the prophets, in this last day, he has revealed himself through his Son, Jesus Christ (Heb. 1:1).
While we can speak of a certain measure of general revelation, it seems that without the specific revelation that comes from the one creator God, we are left with two options. Either he will remain an “unknown God” to us, as he was to the Athenians in Acts 17, or we will add our own “revelation” and make him a false God, as countless world religions have done.
Volf claims that if Muslims and Christians do not worship the same God, then neither do Jews and Christians. However, what Jews and Christians share that Muslims and Christians do not is an understanding of God that is based on biblical revelation. While I would contend that my Jewish friend’s view of God is incomplete, I would say that insomuch as he accurately reflects the special revelation of God in Tanakh, he is speaking of the true God. However, when my Muslim friend bases his view of God on the additional “revelation” of the Quran, I cannot say that he is speaking of the true God, for I cannot affirm that the Quran is the special revelation of God. While Muslims may say some things that are true about God, they do not share this revelatory foundation. Therefore, they are not speaking of the God who has revealed himself in history to a specific people and ultimately through a specific Person.
Imagine two Dallas Cowboys fans having a discussion after the 2008 season. One says to the other, “Roy Williams was really a disappointment this year.” The other, nodding thoughtfully, says, “Absolutely. He only played in a few games for us, and he didn’t do much to earn his paycheck even when he was on the field.” His friend answers, “If only he could match the stats he used to put up Big 12 conference play.” They both sigh.
But then the conversation takes a turn. The second fan continues, “I mean, the guy dropped more passes than a statue.” The first guy, responses with slight confusion, “I don’t think he was ever in position to intercept the ball, let alone drop it! And don’t even get me started on his tackling!” “Tackling?” his friend replies. At this point the guys look at each other and realize they are talking about two different players. You see, in 2008, two different players named Roy Williams were on the Cowboys roster. One was a wide receiver, and other was a defensive back. Both had the same name. Both played the same game. Both wore the same uniform in the pros, and both played college football in the Big 12 conference (one at Texas, the other at Oklahoma). None of this, however, makes Roy Williams, wide receiver, and Roy Williams, defensive back, the same person.
We can say a lot about the similarities in name, character, and activity between the God revealed in the Quran and the God revealed in the Bible. But that does not make them the same person any more than talking about the similarities between the two Roy Williamses does. If someone worships a God who is based on alternative revelation, regardless of how much we might like to smooth over the differences, we cannot affirm that person is worshiping the God of the Bible. To do so would be unfaith to the revelation we have received. We know God only because he has revealed himself to us, finally and fully through the Lord Jesus Christ.
 This paragraph is based on Nathan MacDonald, Deuteronomy and the Meaning of Monotheism (FAT II/1; Tübingen: Mohr Siebeck, 2003).