Whatever happened to liberation theology? Back in the 70s, the big idea was that salvation was unavoidably political. Just as Moses led his people out of slavery, so it was the task of the church to help lead people out of poverty. Inspired by the work of Latin American base communities in the Roman Catholic church, theology became a tool to give the poorest a rallying point for resistance to political oppression, not least in the area of land reform.

But in the early 90s the Vatican became increasingly nervous of priests behaving as revolutionaries. They shut down the base communities and appointed a succession of conservative bishops in places like Brazil to stamp out the creeping influence of Marxism – an ideology that was loathed by the Polish pope John Paul II....