Sacrilege could hardly have a more brutal or blasphemous face. To destroy a shrine as central to Shia Islam as St Paul’s is to Anglicanism is an act of spiritual and religious desecration calculated to exact a bloody human toll. Already, it has done so. Far beyond the borders of Iraq, a country almost inured to suicide bombings, the destruction of the Samarra mosque and the retaliatory attacks on at least 90 Sunni mosques across the country have left Muslims aghast. How long will a few spiritual and political leaders be able to urge restraint before Iraq is plunged into general bloodshed by the incitements of sectarian leaders and retaliatory vengeance — the random murder of clerics, shooting of Sunni prisoners and execution of hostages?

Until now, Iraq’s neighbours have pretended the turmoil on their doorstep was none of their concern, while giving covert and deadly support to some of the extremists leading the insurgency. Now all can see where such irresponsible meddling leads: to polarisation, desecration and the brink of civil war. The reaction has been as depressing as it is familiar. Most of the Arab world, so angrily denunciatory of the insult perceived in the Danish cartoons, has remained silent. Iran’s deluded President has gone further: the destruction of the golden dome at the Askariya shrine was the work of “defeated Zionists and occupiers”, he ranted to a crowd, insisting that the Americans had bombed the mosque because “they oppose God and justice”.

If others in the region hope to halt such reckless incitement before it spills over into their own countries, it is time to do something now. Bloody clashes between the Sunni minority and Shia majority in Iraq will not only wreck that country’s chances of forming a government of national unity; they will also inflame lingering religious animosities across the Muslim world.

No one should be more aware of this danger than Saudi Arabia, a country still struggling with a terrorist challenge inspired by the same religious fanaticism that drives al-Qaeda and the Samarra bombers. The Saudis have a long and shameful record in the treatment of their own Shia minority; and there are still elements within the powerful Sunni clerical establishment that would welcome a continuing crackdown on “heretics”. Condoleezza Rice, who yesterday held talks in Riyadh, had little need to point out the urgency of steps that the wider Muslim world should now take. The first should be an immediate condemnation of the attacks on mosques, Sunni and Shia. Secondly, Iraq’s neighbours — and especially Saudi Arabia — should offer money and expertise to rebuild the Samarra shrine. That would send a clear signal to the country’s Shias that Sunni extremism does not have the backing of Sunni governments. Thirdly, the Arab world, which often calls for greater cohesion and solidarity, should, instead of shunning Baghdad for fear of condoning the allied presence, take a lead in Iraq. Why does the Arab League not rise from its own lethargy and offer political mediation, conciliation and support to the newly elected politicians?

Iraq’s resilience is being tested as never before. It is, however, ominous that religious leaders have begun moving into the trenches with mutual denunciations. The terrorists want a religious war; it is up to Iraq’s spiritual leaders, with the necessary support from the country’s neighbours, to thwart such a dire outcome.