When he was a young boy growing up in a rural rectory in East Anglia, Diarmaid MacCulloch's parents used to drive him around to look at churches. His father, one of a line of Scottish Protestant Anglican ministers, didn't really encourage stops at Catholic churches. But humans are always most interested in what is forbidden, and in the due course of time, MacCulloch grew up to be interested in the multiple ways in which Christianity has morphed, clashed, invented and re-invented itself.
MacCulloch, who teaches the history of the Church at Oxford University, has put his interest into a massive new book called Christianity: The First Three Thousand Years.
That subtitle isn't an error. MacCulloch says it was important to look back over the thousand years that preceded Jesus' birth to see how Christianity shaped itself, and at the timelines of the two cultures that influenced what the religion would become.
"It's really two different sets of thousand years, one of them a Jewish thousand years and the other is a Greek thousand years. And both those lie behind Christianity," MacCulloch says. "These two cultures — Jewish culture, Greek culture — they've got entirely different views of what God is. And then you get a man coming along who people regard as God: Jesus."
Because these followers came from two traditions, an issue arose: Which God?
"A Jewish God [or] a Greek God?" MacCulloch asks. "That fascinating clash seems to be a fundamental thing about Christianity. It makes it a very unstable thing."
Over its nearly 1,200 pages, MacCulloch's book looks at issues that split the church and helped it to grow: the language Jesus spoke, how churches and Christian communities spread after his death, the unpredictability of Rome becoming the center of the Christian world, and why some countries remain resistant to Christianity while their neighbors embrace it.
That question, MacCulloch says, can be reduced to the matter of choice and dignity.
"Often for people who don't have choices in their lives, that is the one thing which they can choose. They can choose to turn to Christ," MacCulloch says. "Again and again, you find groups like African Americans, people who were not given a choice, suddenly making a choice. And that, I think, is the power of so many different forms of Christianity."