Tom Holland doesn’t shy away from the big questions. In his book on the early history of Islam, In The Shadow of the Sword, he questioned the foundation myths of the religion. Many Muslims said he’d never do the same with his own beliefs. Well, now he has. He explains how researching Dominion led him to conclude that the culture of the Western world – even of its secular humanists and its Greco-Roman classicists – is as rooted in Christianity as other cultures are in their own founding religions.