People have a very strong sense that there's something more than just what we see. And unless you can appeal to that religious motivation that people have - to their 'ultimate concern' - you cannot mobilize enough people to change society, and to have the kind of social revolution that many people on the left want. You have to find the connection. What is the connection between your social justice movement, and peoples' religious impulse?

Historian Lilian Calles Barger explores the legacy of liberation theology - as a critique of Christianity under capitalism, a challenge to the conditions of inequality and oppression faced by poor and working class people, and as a resurgent movement with the power to propel social movements today and tomorrow.

Lilian is author of The World Come of Age: An Intellectual History of Liberation Theology from Oxford University Press.