Pastor Thabiti Anyabwile, a former Muslim, interacts with Miroslav Volf’s argument in his new book, Allah: A Christian Response, that one could practice Islam and be 100% Christian. Anyabwile also explains how the fundamental differences in doctrine—particularly regarding the nature of God in the Trinity—are irreconcilable:

[HT: TGC]

Last year, Anyabwile released an excellent book on ministering to Muslims, The Gospel for Muslims (reviewed here). There, he offers three reasons for the necessity of holding fast to the doctrine of the Trinity:

First, because we are bound in humility to accept what God reveals of Himself. After all, we are creatures and He is the Creator; we are finite and He is infinite. Accepting and maintaining the Trinity as central to the Christian faith is to say to God, “I believe You—not others and not myself—as You reveal Yourself.” In short, believing and defending the Trinity is essential to genuine Christian faith and witness.

Second, because to deny the Trinity is to commit idolatry. Here the Christian and the Muslim come to irreconcilable differences. We may not maintain that God is one God in three Persons and at the same time accept that God is radically one with no persons in the Godhead as Muslims believe. That would be to accept a contradiction. And it would be to deny the revelation God gives of Himself, making an idol graven with the tools of our own imagination. God is jealous for His name. He calls His people to “worship [Him] in spirit and in truth” (John 4:24). Surrendering the Trinity turns us away from true spiritual worship of the only living God to idolatry.

Third, we must cling to the Trinity because apart from the Father, Son, and Holy Spirit, there is no possibility of eternal salvation. If we surrender the Trinity, or weaken our presentation of who God really is, we in effect deny the gospel. Each Person in the Godhead plays an essential part in redeeming sinners from judgment and bringing them to eternal life. (p. 37, Kindle edition)

A tool that some find helpful in evangelism is a series of diagnostic questions. “Have you come to the place in your spiritual life where you know for sure that if you were to die tonight you would go to heaven?” “If you were to die tonight and stand before God, and God were to say to you, ‘Why should I let you into My heaven?’ what would you say?”

Some might bristle at the thought of asking these questions, for fear of being linked to Ray Comfort and Kirk Cameron (that said, who wouldn’t want to go out street preaching with Mike Seaver?). But they’re actually more helpful than you might think. R.C. Sproul explains:

Once, when my son was young, I asked him these two questions. I was delighted that he immediately answered the first question by saying “Yes.” But when I asked him the second question, he looked at me as if I had just posed the silliest question he had ever heard. He said, “Well, I would say, `Because I’m dead.”‘ What could be simpler? My son was being reared in a home committed to biblical theology, but not only had I failed to communicate justification by faith alone to him, he already had been captured by the pervasive view in our culture that everyone goes to heaven and that all you have to do to get there is to die.

We have so eliminated the last judgment from our theology and expunged any notion of divine punishment or of hell from our thinking (and from the church’s thinking) that it is now widely assumed that all a person must do to get to heaven is to die. In fact, the most powerful means of grace for sanctification in our culture is to die, because a sin-blistered sinner is automatically transformed between the morgue and the cemetery, so that when the funeral service is held, the person is presented as a paragon of virtue. His sins seem to have been removed by his death. This is very dangerous business, because the Scriptures warn us that it is appointed for every person once to die, then to face judgment (Heb. 9:27).

People like to think that the threat of a last judgment was invented by fire-and-brimstone evangelists such as Billy Sunday, Dwight L. Moody, Billy Graham, Jonathan Edwards, and George Whitefield. But no one taught more clearly about the last judgment and a division between heaven and hell than Jesus Himself. In fact, Jesus talked more about hell than He did about heaven, and He warned His hearers that on that last day, every idle word would come into judgment. But if there’s anything unredeemed human beings want to repress psychologically, it’s that threat of final, comprehensive judgment, because none of them wants to be held accountable for his sins. Therefore, nothing is more appealing to human beings than universalism-the idea that all are saved.

R.C. Sproul, Can I Be Sure I’m Saved? (Kindle Edition)