Do Christians and Muslims worship the same deity? It has become one of the most pressing and controversial questions in the world in the last fifteen years.

The question was stirred up in earnest in 2001 in the aftermath of fundamentalist Muslims flying hijacked commercial jetliners into the twin towers of the World Trade Center in New York. And tragically the question has been stirred up time and time again in the decade and a half since, after a wave of major terrorist attacks, undertaken in the name of Allah. Recent months have brought large-scale tragedies in Paris, Orlando, Istanbul, Baghdad, and now Nice, France.

After each attack, fresh voices either demonize Islam or seek to dispel any notions that Islam itself might be the problem. But however important the sociology and politics may be for secularists, beneath it lies the all-important question for Christians and Muslims: Is the Islamic notion of Allah compatible with the Christian belief in God?

I had the privilege of putting the question to D.A. Carson, world traveler and world-class scholar, co-founder of The Gospel Coalition, and author of Love in Hard Places, in which he addresses some of the challenges related to Islam. Do Christians and Muslims worship the same God?

“I wish I could give you a simple yes-no answer that would be definitive,” says Carson. “My bottom line is no — but you have to get there carefully.”

The Historical Connection

First, Carson notes the historical-genetic connection. “It’s not as if Christianity and Islam began in separate silos. Islam came out of Christianity and the Nestorian form of it that they reacted against.”

Nestorius (386–450) was the influential bishop of Constantinople. Whether or not his own views of the person of Christ were orthodox, the two-person heresy condemned at church councils in 431 and 451 bears his name. Christian theology recognizes the incarnate Christ as one person, the eternal Son, with two true and complete natures — fully human and fully divine. Nestorianism compromises the singular personhood by failing to recognize the one-person (“hypostatic”) union of the divine and human in Christ, thus observing, whether explicitly or what amounts to, not just two natures, but two persons in Christ.

It was this heretical form of Christianity that Islam’s founding prophet, Muhammad (570–632), encountered through interactions with multiple Nestorians in his upbringing.

“There is a historical connection of some sort,” says Carson. “Which is not the same for example with Christianity and Buddhism or Hinduism.

“Moreover, Christianity, Judaism, and Islam are the only three big monotheistic religions so there’s a certain commonality there. This leads to a point of continuity. For example, both Christians and Muslims believe that God created everything; that God is just; that sin, fundamentally, ignores or defies God; that we need forgiveness; that God is the final Judge.”

What Devout Muslims Believe

Beyond what’s shared merely at the surface level, one often overlooked consideration is this: What do Muslims themselves think about our sentimental notions of commonality and lowest-common-denominator bridges for dialogue?

“The most devout Muslims that I know don’t like to be told that Christians and Muslims have the same God. ‘Of course, we don’t have the same God,’ they say. ‘It seems like you believe in three gods.’ Even if they’re trying to be a little more sympathetic and say, ‘You believe in the Trinity and all the Son-of-God stuff (that’s just rubbish), you don’t have the same God as we have.’ Indeed, in some Muslim countries, Malaysia for example, it’s now forbidden by law for Christians to use the term Allah to refer to God. They must have another term.

“Meanwhile, our desire over here to say that we all worship the same God is driven less by exegesis and theology than it is by the kind of sentimental notion in the West that we’re really all saying the same thing after all. It’s not driven by rigorous thought. It’s driven either by social sciences or by a sloppy form of missiology that is constantly looking for the lowest common denominator to build bridges.”

What the New Testament Makes Clear

“After listing points of continuity, honesty demands that we list points of discontinuity,” says Carson. “For example, there are the explicit biblical texts that say that if you don’t recognize the Son, you don’t recognize God himself, especially in John’s Gospel and 1 John.”

Serious Christians, no doubt, won’t be content simply to take their cues from the honest confessions of serious Muslims. We have our own holy Book — which we believe to be the very words of God. And when you look at the Book, this is what God himself says about Jesus being the litmus test:

• John 5:23: “Whoever does not honor the Son does not honor the Father who sent him.”

• John 5:42–43: “I know that you do not have the love of God within you. I have come in my Father’s name, and you do not receive me.”

• John 8:19: “If you knew me, you would know my Father also.”

• 1 John 5:12: “Whoever has the Son has life; whoever does not have the Son of God does not have life.”

Whatever the merit or naiveté of Western sentimental notions of commonality among monotheists, Christians who honor God’s own word as authoritative must take into account these clear assertions that those who do not know, love, honor, and have life in the Son do not know, love, honor, and have life in the Father.

“The ground of forgiveness appealed to by each of the two religions could not be farther apart. For the Muslim, God forgives some people, at his own sovereign discretion, on the basis of his assessment of their life. For the Christian, God forgives the people he has savingly loved from all eternity on the ground of the death and resurrection of his Son. The cross ensures that God is both just and the One who justifies the ungodly who have faith in Jesus. Here there is hope, transforming hope, in a powerful ‘good news’ that reconciles sinners to God without impugning God’s justice.”

Disagree with Respect

Carson acknowledges that those who want to “lower tensions between people with a Christian background and people with a Muslim background” often have good intensions. “But to my mind, there’s much more likelihood of courtesy from Christians who know how to disagree with respect than from people who are saying that we actually all believe the same thing.”

Better than minimizing the differences between the central beliefs of Christianity and Islam — and they are central and significant — is acknowledging the differences and modeling disagreement with courtesy and respect.

Does God Make Himself Vulnerable?

One central difference, among others, which Carson draws attention to is what we might called “the vulnerability of God.”

“Allah in the Qur’an is a God who finally is sovereign and our judge. He’s beneficent, he’s all-merciful, but he’s not known as the God of love. It’s partly because in Islam, the sovereignty of God is so stressed — his transcendence and sovereignty are so stressed — that to speak of God as loving makes him vulnerable.

“From the Muslim point of view, to talk of God being love is reducing God. It’s making him more vulnerable. Christians have a weak God from their point of view.

“Yet, the fact of the matter is that while the God of the Bible is no less sovereign than Allah is, within the contours of Islam, yet the God of the Bible does make himself vulnerable. He turns himself into, if you please, the almighty cuckold in Hosea, and elsewhere he says, ‘Turn, turn, why would you die? The Lord has no pleasure in the death of the wicked’ (see Ezekiel 18:23; Ezekiel 33:11). Somehow, this vulnerability has to be worked out theologically with what the Bible says about God being utterly sovereign and above time and space and transcendent and all the rest. But that’s a much more complex picture.”

Such vulnerability is not tangential to the Christian notion of the divine, but gets at the very heart of the faith in the central message. The Son of God humbled himself, took on our frail humanity, and died an ignominious death to reconcile sinners to God. Ultimately, we cannot minimize the differences between Christianity and Islam without minimizing the essence of the gospel.

True Love for Neighbor

To the uninitiated and uncareful, some forms of Christianity and Islam may seem to have so much in common on the surface as monotheistic faiths. But as you dig into what the respective faiths claim, in their most central and important aspects, the differences are massive. It’s not only Christology — and the insurmountable barriers the New Testament erects — but it’s also the attributes of God. To say that Christians and Muslims are essentially worshiping the same deity is to seriously misunderstand or compromise one or both faiths.

As people continue to ask the question worldwide about the world’s two largest faiths, this is “just one more case,” says Carson, “where Christians are going to have to think carefully and articulate wisely. We won’t convince everyone, of course — we never do — but we want to make sure that what we say is the truth about both Christianity and Islam.”

True love for neighbor won’t play fast and loose with our neighbor’s central beliefs — or our own. The opportunity to truly love begins with honesty about our differences.