The standard replies to views as one-sided as these are familiar. I took a different line, reminding my driver that overall, Christians - starting with more than a million church members butchered by government forces in Sudan - have endured far worse treatment from Muslims than vice versa in recent decades but have largely keep quiet about it. When I pointed out that there is scarcely a country between Morocco and Pakistan in which Christians are fully free to worship without harassment, the cabbie eyed me with bewilderment.

His blind spot is shared by many a liberal secularist who would normally be among the first to speak out on minority rights. The reason for this malaise stems from ignorance, as well as a hierarchy of victimhood. Many assume that Christianity is a Western faith and therefore an import to the Middle East, rather than an export from it. The point is encapsulated by the anecdote about an American general who once asked an Arab Christian when his family had converted. "About 2,000 years ago," came the wry answer.

The plight of Coptic Christians in Egypt is especially tragic, long predating the worsening regional situation triggered by 9/11 and regime change in Iraq. Copts still form about 12 per cent of the population but used to be more numerous. To the consternation of Islamists who are in denial about the Middle East's mixed religious ecology, the very word "Copt" derives from the Arabic Qibt, an abbreviation of Aigyptos, the Greek word for Egypt.

Some members of this ancient Church have prospered. The ranks of well-known Egyptian Christians have included Boutros Boutros-Ghali, the former Secretary-General of the UN. Egypt's legislative assembly has contained Coptic members since 1922.

But 600,000 Egyptian Christians have emigrated over the past 30 years in the face of systematic discrimination and violence - including the regular bombing of churches by militants influenced by Saudi-derived extremist ideologies.

The discrimination is less dramatic, but equally insidious. As an Egyptian-born doctor now based in Britain told me, "When I was at medical school Christian students were either passed or failed; not a single one was placed in the 'Good', 'Very Good' or 'Excellent' categories." This meant that none would achieve a high-flying career.

A bad situation has become calamitous as Egypt has fallen into further instability. Numerous anti-Christian attacks, especially in Upper Egypt, have passed largely unreported in the West. Earlier this month, for example, a march by supporters of the ousted president, Mohamed Morsi, in the village of Dalga, near Minya, turned violent. Protesters attacked property belonging to the local Coptic church, St George's; burnt down the priest's house; and threw Molotov cocktails at Christian-run shops and businesses. St George's itself was looted and torched. A nearby church was fired on. As often in the past, some Muslims rushed to the aid of their Christian neighbours. The authorities looked the other way.

Several days later a priest at Masaeed in northern Sinai, Fr Mina Abboud Shaoubim, was dragged from his car by militants and shot nine times. He later died of internal bleeding. Look on the English-language website of Watani, the Coptic newspaper, and you can read solid evidence about allied atrocities.

Last week, Amnesty International released a dossier on other recent assaults on Egyptian Christians. In the worst instance an angry mob, armed with metal bars, knives and hammers, murdered four Coptic men and injured others in Nagah Hassan, 11 miles west of Luxor. More than 100 Christian homes were attacked: of these, scores were torched and looted. Local residents said they had called police and army hotlines throughout the day in vain.

For all its chronic problems, however, Egypt has not yet descended into civil war. It is Syria's Christian community that is now staring into the abyss.

Reliable information is hard to come by in the midst of a bloodbath. But the charity Aid to the Church in Need estimates that hundreds of thousands of Christians have fled their homes over the past two years, especially residents of Homs, Damascus and Aleppo. Priests including Fr Fadi Haddad, from the city of Qatana, have been kidnapped, tortured and murdered.

Christians are vulnerable because the Assad regime, despite its many other crimes, has protected religious minorities. For this reason church leaders, including Patriarch Gregory III of Antioch, have begged the outside world not to send in more weapons. Some observers predict a regional war with potentially catastrophic global consequences if Assad is replaced by a regime including Sunni radicals. If this happens, the indigenous Christian presence in the churches' biblical heartlands may be eliminated.

I feel proud to live in a city like London which has often (if sadly not always) shown hospitable instincts to Muslim immigrants, and which is now one of the world's major Islamic centres.

But many Muslim-majority countries - admittedly more tolerant than most European societies in earlier eras - are failing to return the compliment at present. Sometimes a senior cleric will speak out. The Grand Mufti of Egypt, Dr Ali Gomaa, has regularly condemned Islamist terrorism. He might have added that the future peace of the world hinges in part on good Muslim-Christian relations.

The heroism of countless Christians under fire around the world (by no means in Muslim-majority countries alone) is in many ways humbling. But their rights are being abused, and the double standard needs to be laid bare.

Rupert Short's book Christianophobia: A Faith Under Attack is published by Rider.