LONDON — One of the most obvious transatlantic contrasts is the role of religion in politics. In American politics, religion is usually overt; in Europe, it is usually covert. In America, a candidate who parades his piety may hope to be rewarded; in Europe, that candidate would more likely be punished.

That, at least, is the received wisdom. It lies behind the petulant response of Tony Blair’s spokesman, Alastair Campbell, when the then prime minister’s faith came under the spotlight: “We don’t do God.” No sooner does religion appear in the European public square, than it is firmly put back into a box marked: “Private.”

The truth was, though, that Mr. Blair kept “doing” God while still in office. He was accused of praying on his knees with President Bush (he didn’t) and of secretly planning to convert to Catholicism (he did, though only after leaving office).

The global jihad that long predated September 11, 2001, but could no longer be ignored thereafter gave critics another reason to accuse him of pressing God into the service of his own crusade. Only “nuances” separate Mr. Blair’s zealotry from Al Qaeda’s, the newspaper columnist Rod Liddle absurdly claimed this week.

Nearly a year after leaving Downing Street, Mr. Blair has already acquired a portfolio of jobs that would keep most former statesmen fully occupied: Middle East envoy for the “Quartet” of America, E.U., United Nations, and Russia; adviser to various prestigious corporations, such as J.P. Morgan; part-time professor at Yale; and leading candidate for the new office of President of Europe.

Now, however, Mr. Blair is launching a new Faith Foundation, which he insists will be “the rest of my life’s work.” He wants to save religion from the double threats of militant secularism and extremism.

At a lecture he gave last week in Westminster Cathedral, Mr. Blair spoke about the importance of tolerance and respect toward others. Outside, a deafening din of drums and whistles was set up by thousands of anti-war demonstrators who surrounded what is, after all, a place of worship. They showed real venom not only toward the former prime minister, but also the ordinary people who had come to hear him bear witness to his faith.

Whence did the hatred come? There are, of course, perfectly respectable reasons for having opposed the invasion of Iraq, but it is a dangerous delusion to claim that a global crusade is now being fought by the West against Islam.

Yet many people believe in this delusion, both Muslims and non-Muslims, even though it is the opposite of the truth. It struck me that the real persecution of Christians and Jews, not only in the Muslim world but also in China and elsewhere, arouses no such passions here.

After his lecture, I asked Mr. Blair whether he agreed with Pope Benedict’s analysis of Islam at his Regensburg lecture in 2006. The Pope had contrasted Christianity and Judaism, on the one hand, and Islam, on the other, over the question of faith and reason. The Judaeo-Christian traditions had absorbed the Greek idea of reason, while the God of Islam was not subject to rational constraint at all.

Mr. Blair is too wily a politician to be caught out by such a question. He agreed with the Pope, he said, who had been much misunderstood — an understatement, given that his words about the prophet Mohammed, though quoting a medieval Byzantine emperor, were used to justify violence across the Muslim world.

Benedict’s aim had been to promote good relations between Catholics and Muslims. But Mr. Blair also was certain that faith and reason went hand in hand in all the major world religions. I don’t see how that is compatible with the Pope’s view.

Still, I respect Mr. Blair for rejecting moral relativism and standing up for the right of people of faith to be heard in the public square. Many are understandably scathing about his liberal record on moral issues, from abortion to gay marriage to stem cells. They accuse him of hypocrisy because he did not practice in office what he preaches now.

Margaret Thatcher, who is still by far the most popular choice as Britain’s greatest post-war prime minister, was braver and more consistent.

But I have some sympathy for Mr. Blair. He could not fight on every front and for him the war on terror became the defining issue of his premiership. On that he was courageous.

I wish the Faith Foundation well. And I suspect that we have not heard the last of Tony Blair, who is a powerful voice on behalf of those who believe that the world has no meaning without the spiritual and moral dimensions that only religion provides.

Mr. Johnson is the editor of Standpoint magazine.