Liberation theology was a movement that grew in South America. The aim of the movement was for the church to act to bring about social change for the poverty and the bad treatment of ordinary people. In the 1950's, 1960's and before the government were like a dictatorship and they seen no problem with the social divide (the poor people living in favelas and shanty towns on the brinks of society and the rich middle class people living in big cities). Many priests took a stand and spoke out against the social injustices and the government in mass. Some priests stood for election with the hopes of making a change, this is the real meaning of liberation theology, taking a stand for the weaker people, and we see a return to origin through their actions of standing up for the poor and needy.
Others went the route of theology revolution which is the just war theory. Priests and nuns took up guns and fought (literally) for the equality of their people. Many priests, nuns and religious workers turned and joined military groups and fought. This is not seen as a return to origin as Jesus was never really violent, except for the overturning of the money changers tables in the Temple and that is the excuse these radical rights activists use for their use of violence.
Oscar Romero was the Archbishop of San Salvador in the growing years of liberation theology. Romero was very outspoken about the poverty and ill-treatment of the people of San Salvador, he set up free legal aid to help innocently arrested by providing lawyers who gave their services for free. Oscar Romero was very critical about the government and their oppression of the people who have very little, because of his plain-spoken opinions he was assassinated in an organised murder by the government during a mass in 1980.