Christianity in the Middle East is ancient and, with its denominational oddities, is often confusing for Westerners. But there is no excuse for confusion in Saudi Arabia, which has recently become home to one of the Middle East's larger (mostly Western Catholic or Protestant) Christian populations. The Saudi authorities systematically oppress the million or more Christians who work there. These are largely uninfluential menials — Filipinos, Africans and Asians — which makes it less internationally troublesome. Saudi Arabia allows no non-Muslim worship, even in private homes; Bibles cannot be distributed; display of the cross (even on a footballer's jersey) is banned. These laws are given effect by the feared religious police. In February, for example, they swooped on a private gathering of more than 50 Ethiopian Christians and threw the leaders in jail. 

The United States provides billions of dollars in aid to Egypt, but it will not use it as leverage for the Copts. US power underpins Saudi security, but it had nothing to say when (in March 2012) the Saudi Grand Mufti, a high state official, declared it "necessary to destroy all the churches" in the region. The new US Secretary of State, John Kerry, has form. When US Representatives Frank Wolf (Republican) and Anna Eshoo (Democrat) co-sponsored a bill to create a special envoy position within the State Department to advocate on behalf of religious minorities in the Middle East, it was blocked in the Senate by the Foreign Relations Committee, then chaired by Kerry. President Obama's gesture of support for Christians in Bethlehem last month does not make up for years of negligence.

As for Britain, the hypocrisy is even more revolting. The Coalition government insists on prioritising overseas aid, even at the expense of the defence budget. David Cameron takes a special interest. He has publicly threatened to cut aid to countries that oppress homosexuals. But he won't consider applying that threat to countries that persecute Christians. Indeed, the sum total of Britain's action to protect Christianity from extinction in the Middle East is a list of low-level, low-key initiatives, undertaken by junior ministers or unimportant officials, which (as Mrs Thatcher used to say) "wouldn't knock the skin off a rice pudding".

But does it matter? If you really believe that systematic persecution is wrong, it does. But who in the upper reaches of Western governments really believes that today? And, naturally, the notion that Christian countries should protect Christians is so preposterously incorrect that no modern politician would suggest it. But there is one argument, which even the most hardened critic of morally driven foreign policy should consider.