In the past few decades, Central America has been in the grip of what has been described as the largest mass conversion in history - the explosive growth of Pentecostalism across Latin America. The take-up of this new faith in both Guatemala and El Salvador is now estimated at over 40%.
Film maker Steve O'Hagan travelled through those countries to ask why the people there are reaching out to this new religion, after 400 years of rule from the Vatican.
Forty years ago, a radical new Catholic offshoot known as Liberation Theology looked set to transform Central American society as the theological wing of the socialist-inspired revolutions that were erupting across the region. In a conservative backlash, Pentecostalism became the faith of those who opposed these revolutions and wanted to keep the status quo. The two movements found themselves on opposite sides in the brutal civil wars of the 1980s and 90s.
From the space-age opulence of the biggest church in all of Latin America on the outskirts of Guatemala City, to the rapidly mushrooming micro-churches operating out of back rooms and alleyways of the working class suburbs of San Salvador, Steve O'Hagan searches for the reasons why Pentecostalism - a faith associated with wealth, televangelists, and the North American Right - has proven so successful here.
Increasingly from the margins of the society, the Catholics of Liberation Theology continue to dedicate themselves to their work. In the mountainous former rebel strongholds of El Salvador, Steve meets a Belgian priest who ministered to the guerrillas throughout the 12-year civil war and today is still tending his flock.
But in a surprising coda, we discover that perhaps the spirit of Liberation Theology will live on in its theological 'conqueror'. Some Pentecostal groups in El Salvador are beginning to cast off the right-wing tendencies of their past, and pick up the torch of liberation first lit by the Catholics decades earlier.