Many people, Catholics no less than non-Catholics, are bewildered and dismayed by the sudden firestorm of Muslim hostility that has overtaken Pope Benedict XVI since his lecture in Regensburg last Tuesday.

The most charitable interpretation, said one BBC correspondent, is that he is culpably naïve — that he simply forgot that he was speaking not as a scholar to his peers, but as pope. Even his defenders have suggested that it was a faux pas to quote a 14th-century Byzantine emperor on the subject of Muhammad. Surely, they say, it was an aberration for the spiritual leader of more than a billion Catholics to use words such as “evil and inhuman” to describe the prophet of more than a billion Muslims. Was it not inconsistent, to say the least, to preach tolerance while accusing Islam of intolerance?

Well, no: The passage that has aroused the ire of the ayatollahs was not a faux pas, still less an aberration. And Benedict is nothing if not consistent. From his earliest days, he has been true to his vocation as a priest and as an intellectual. In the words of Milton’s “Paradise Lost,” he set out to justify the ways of God to men, and he realized from the outset that he could do this only by appealing to reason.

Günter Grass, in his memoirs, recalls an encounter with the young Joseph Ratzinger while both were held in an American prisoner-of-war camp in 1945. The young Grass, a Nazi who had been proud to serve in the Waffen-SS, was taken aback by this soft-spoken, gentle young Catholic. Unlike God, the future pope played dice, quoting St. Augustine in the original while he did so; he even dreamt in Latin. His only desire was to return to the seminary from which he had been drafted. “I said, there are many truths,” wrote Grass. “He said, there is only one.”

Sixty years later, just before the conclave that elected him pope, Ratzinger proved that he had never changed. The then prefect of the Congregation of the Faith — in effect, the church’s theological backstop — preached a sermon to the assembled cardinals in which he denounced the “dictatorship of relativism.” From that moment on, there was no other serious candidate.

This is not the kind of Christian who fudges issues or asks, like Pontius Pilate: “What is truth?” On the contrary, Benedict is secure enough in his beliefs and intellectually confident enough to be able to engage in lively debate with such hostile interlocutors as the postmodernist philosopher Jürgen Habermas.

Benedict believes passionately that people of faith in general, and Catholics in particular, must either fight for their corner in the intellectual arena or shut up shop. Jewish or Christian morality and theology deserve a prominent place in the public square, not merely in private life.

He is, of course, the first pope to be elected since September 11, and he sees the conflict between Islam and the West as the most serious issue of our time. Though his public statements about Islam are few, the line is a firm one. The Benedict watchword is “reciprocity” — Muslims must accord other believers the same religious freedoms that they themselves enjoy in liberal democracies.

Just as John Paul II was not afraid to take on the godless ideology of communism, so Benedict XVI is not afraid to denounce the fanaticism of Islamo-fascism. Yesterday he called for a “frank dialogue, with mutual respect.” Though he was at pains to remove misunderstandings, there was no hint of a retraction.

It is not that the pope believes himself to be infallible — a concept that applies only when pontiffs speak ex cathedra with the full authority of the church, past as well as present. Here, Benedict refuses to back down because he cannot tell a lie.

So what was the pope really saying in that lecture he gave in Regensburg, his old stamping ground in Bavaria? It was a rich and elegant reflection on the rationality of faith, couched in the erudite language of a very German philosophical discourse.

But the message was, at heart, a straightforward one. The Jewish or Christian God acts in accordance with reason: In the beginning was the Word, the Logos. Benedict emphasizes that this new, logocentric understanding of God is already present in the Hebrew Bible, long before the fusion of Jerusalem and Athens in the New Testament. Our knowledge of God — the God of Israel or the God of Christianity — emerges in the unfolding of the encounter between faith and reason.

The contribution of Hellenic thought to this gradual enlightenment is, for Benedict, essential. He laments the “dehellenization” of Christianity since the Reformation. Its effect, he thinks, has been to “relegate religion to the realm of subcultures” and to treat scientific rationality as if it had nothing whatever to do with faith. “The West has long been endangered by this aversion to the questions which underlie its rationality,” he warns. If the West ignores this theological perspective, it “can only suffer great harm.”

But the Pope was saying that there is an alternative to the Jewish or Christian God: the God of medieval Islam. Allah is “absolutely transcendent,” above even rationality. Benedict cites a Muslim authority to the effect that “God is not bound even by his own word.”

It is in this context that the pope invokes the Emperor Manuel II Paleologus, who recorded his dialogue with a learned Persian Muslim about the year 1400. Byzantium would finally succumb to Turkish conquest only half a century later, and Manuel wants to know how the doctrine of jihad can be justified, given that it is incompatible with God as Logos. For this Hellenic Christian, Muhammad’s command to spread Islam by the sword must indeed be “evil and inhuman.”

Yesterday, the pope insisted that he did not agree with Manuel. But it is clear that he sympathized with this monarch of a doomed Christian civilization enough to use him as a mouthpiece through which he could pose his own implicit questions to Islam. Does the Muslim understanding of Allah allow rational debate about the morality of violence, given that the doctrine of jihad is a central pillar of Islam? If Allah is above reason, might violent jihad, including terrorism, be not merely justifiable but obligatory, as many Muslim scholars argue?

By now, the answer to these questions is clear: churches firebombed in the West Bank and Gaza, a nun murdered in Somalia. Such persecution is, alas, routine in many Muslim lands, and Catholics are not the only victims. But it is clear that Muslim leaders — even those of “pro-Western” countries such as Turkey or Pakistan — are not yet ready for the “frank” dialogue proposed by the pope. By pointing out that violence is a part of medieval Islam, not a “distortion,” as Western liberals like to think, Benedict has touched a raw nerve.

No, this pope is not naïve. It is our liberal, theologically illiterate politicians who are naïve. We are already at war — a holy war, which we may lose.

Nor is he inconsistent. The Ratzinger of old, his skill in disputation honed over many years of patiently defending Catholic orthodoxy against liberal or secular opponents, was never going to duck the long-postponed doctrinal confrontation with Islam. In his subtle, scholarly way, he is urging the rest of us to face the fact that if we have no faith, we cannot hope to withstand the onslaught of a resurgent Islam.

Benedict is well aware of the risks, not least to his own life, of speaking out. Like his great Polish predecessor, this “German shepherd” has the courage of his convictions. Thank God he does: Without convictions, our courage will surely fail us.