In Benedict's view, a profound ambiguity about violence lies at the heart of Islam, arising from the Prophet's belief that faith can be spread by the sword. Mohammed, after all, was a general whose troops beheaded hundreds of enemy captives.

Asked recently whether he considered Islam to be a religion of peace, the Pope replied: "Islam contains elements that are in favour of peace, just as it contains other elements." Christianity, by contrast, he sees as a religion of pure peace — which is why he adopts a near-pacifist approach to conflict in the Middle East.

Where the pontiff differs from his predecessor is in his impatience with what might be termed "Islamic political correctness".

John Paul II hoped that prayer could bring Christians and Muslims closer together, and famously prayed alongside Islamic leaders at Assisi in 1986. He also reassured Muslims that "we believe in the same God".

Benedict would emphasise that the Islamic understanding of God is radically different from that of Christians.

He has also refrained from issuing the apologies for historical misdeeds made by John Paul II, arguing that they are never reciprocated.

Last year, at a private seminar, the Pope implied that he agreed with conservative Muslim clerics that the teachings of the Koran cannot be modified in any way. More-over, Islam, unlike Christianity, makes no distinction between sacred and secular.

"The Koran is a total religious law," he wrote in 1996, "which regulates the whole of political and social life." Therefore, a devout Muslim living in the West must aspire to live under sharia law. A multi-faith society "is not consistent with Islam's inner nature".

In other words, the Pope subscribes to a version of the "clash of civilisations" theory, which sees a fundamental incompatibility between Western and Islamic cultures. In his opinion, the primary aim of Christian-Muslim discussion is to avoid conflict.

For example, he supports the right of Muslim children to be taught their own religion in European schools — but on the strict understanding that their communities respect human rights.

Benedict's lecture at Regensburg University merely sought to elaborate his existing views. Beautifully written and constructed, it was intended for scholars interested in the relationship between God, rationality and coercion.

Although he described the Muslim approach to violence as defying God-given rationality, the Pope had no intention of offending ordinary Muslims or creating media headlines.

Yet the leader of the world's Roman Catholics has done both. How could a man who is so notoriously careful with words have committed what, in the eyes of liberal society, is a diplomatic blunder? The answer may be that underlying Benedict's nuanced world view is a deep-seated fear of Islam, which crops up in the daily conversation of Italian Catholics and stretches as far north as his Bavarian homeland.

He does not believe that the Koran condones terrorism; he bears no animosity towards peace-loving Muslims; but he is worried that the aggressive ethos of authentic Islam may provoke a crisis in Western society. And if the price of making that point is a "diplomatic blunder", then so be it.

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