Holy war rhetoric was particularly strong. Germans described the war as a ‘moral test’ and fell back on crusader imagery. Britain, too, evoked the crusades, and the symbolism of recapturing Jerusalem from the Ottoman Empire was provocative. It is no coincidence that premillennialism flourished at the time, with such portentous signs abounding.

At the same time, as had happened in Europe for centuries, heightened Christian language mingled with superstitions and an interest in the occult. Germany’s top military adviser was a rabid occult follower, as well as a devotee of Nietzsche. The Allies could point to these facts as evidence of the enemy’s anti-Christian nature, but they were equally susceptible to visions, premonitions, and attempted contacts with the dead.

In general, theologians were reluctant to go against the tide of warmongering, and prominent theologians such as Adolf von Harnack waved the nationalistic flag fervently. In Germany liberal theology had become intertwined with the march of modernity and nationalism, and it didn’t help that the Reformation’s 400^th anniversary fell during the war. Clergy from both sides supported the war, even if they had some reservations about soldiers being equated with saints, and many argued that war was good for the moral fortification of young men, though clergymen had to wilfully ignore Christ’s teaching and example to do so. This was easier when, as in Germany, they could resort to using (and abusing) Luther’s ‘Two Kingdoms’ theology. The language of sacrifice, which Jenkins suggests was less of a ‘euphemism’ than it is today, abounded.

But after the war there was what Jenkins describes as almost an embarrassment over the earlier use of religious language and he suggests that we do not find the same overtly religious rhetoric in the Second World War. It is fair to see the roots of Europe’s secularisation here. As Terry Eagleton notes in his latest book, WWI should have killed off faith in humanity rather than faith in God, but the idea that God had a purpose for the world took a battering. In time, it was hard to make moral sense of a conflict where both belligerents claimed God was on their side.

But this is not the whole story. As the subtitle of his book suggests, Jenkins also notes the changes to religion made by the reorganisation of empires. Jenkins notes the creation of Israel, the religious partition of the subcontinent, the consolidation of Islam in the Middle East and the rise of evangelical Christianity in Africa. While the war may have shaken the religious world, it led to redistribution, not decline.