But since leaving Downing Street, Mr Blair has converted to Roman Catholicism and become increasingly open about the importance of religion to his thinking.

Writing in the New Statesman - guest-edited this week by Mr Campbell - he suggested that even while still in office he felt that religion was a key to understanding the modern world.

And he suggested that religious faith may be as significant to the new century as political ideology was to the last, which was racked by struggles between communism, fascism, liberalism and socialism. ...