EVERY so often a question that seems purely abstract and philosophical passes into the realm of hard reality where people's lives and destinies are determined. One such conundrum is whether or not Christians and Muslims can be said to worship the same God. For nearly a decade, the question has preoccupied judges, politicians and ordinary folk in Malaysia, a country where Islam is the most widely-followed faith but large minorities follow other faiths, including Christianity. In 2007, a court ruled that non-Muslims (and Christians in particular) could not use the word "Allah" although that happens to be the Malay or Bahasa word for God. The Islamic authorities reasoned that Muslims might be confused, and tempted to go astray, if they came across people of other persuasions addressing a deity which only Muslims fully understood. In the course of many legal battles, this view has prevailed; Christian printed matter using the word "Allah" has often been impounded as a result.

In 1965, the Roman Catholic church approached the question in a very different spirit, in its landmark treatise, Nostra Aetate. A key passage states:

The Church regards with esteem also the Muslims. They adore the one God, living and subsisting in Himself, merciful and all-powerful, the Creator of heaven and earth, who has spoken to men; they take pains to submit wholeheartedly even to His inscrutable decrees, just as Abraham with whom the faith of Islam takes pleasure in linking itself, submitted to God.

But when Larycia Hawkins, an African-American assistant professor at Wheaton College, an evangelical campus near Chicago, voiced similar views last month, she created a firestorm. She was suspended from teaching, and procedures which could lead to her dismissal were initiated. It all started with a Facebook posting in which she declared her intention, as an act of friendship with stigmatised Muslims, to wear a hijab to work in the run-up to Christmas, and added: "I stand in religious solidarity with Muslims because they, like me, a Christian, are people of the book. As Pope Francis stated last week, we worship the same God."

When challenged by the college authorities about what she believed, she replied with a statement of stricter theological orthodoxy than many a liberal or "mainline" Protestant cleric would be able to make: "I believe in one sovereign God, eternally existing in three Persons: the everlasting Father, his only-begotten Son Jesus Christ our Lord, and the Holy Spirit, the giver of life..." On the commonality between the two monotheisms, she had something more enigmatic to say. After citing various Catholic and Protestant sources, including Nostra Aetate, she added:

Like them I acknowledge that the statement "we worship the same God" is a simultaneous "yes" and "no" to the question of whether Christians and Muslims (as well as Jews) turn to the same object of worship...

Yes and No? That's where philosophy may be able to help. In 1905, the great British philosopher Bertrand Russell started a century of discussion by penning a famous essay showing how an apparently simple statement can in fact be asserting many things at once. Specifically, to say, "the king of France is bald" is to imply both that i) there is a king of France, and only one of them and ii) that sovereign has a hairless scalp.

Compared with that assertion about the royal pate, the statement that "Christians and Muslims worship the same God" is much more complex and multi-layered, and it means entirely different things on the lips of different people. If you are an atheist and think that all "gods" are human constructs, then it is true, in a sense, that every worshipper's god is different, because slightly different constructs are being made. If you are a monotheist, convinced there is only one transcendent deity, then discussion about "the same" God or different ones doesn't make much sense. God is God whether or not people have the right ideas about Him. If you are a polytheist, then it is logically possible to discuss whether two groups of people worship the same god; but on that view, both Christians and Muslims must be radically mistaken.

In the philosophical debate about the royal pate, everybody agrees on an important background fact: with due respect to claimants from the House of Bourbon, there is no king of France. So the statement about his scalp is false. But there is no consensus on the crucial "background fact" in the Christian-Muslim question: do one or more gods exist? For that reason, it is almost impossible to discuss; and certainly not an appropriate yardstick to assess the suitability of a professor.