Liberal theology and liberation theology are two different understandings with distinct histories and views.
Liberal theology did, indeed, grow out of the late 19th and early 20th centuries and was the purview of European white males. Influenced by Darwin's theory of evolution, liberal theologians believed that humankind was continually making progress, evolving and advancing in knowledge and in conquering the unknown. Science and technology were understood by liberal theologians as the means of God toward a world where industrialization and mechanization would produce an easier life for all. Government existed to foster this progress.
Liberal theology was in many ways shattered by the first and second World Wars, in the face of which few could believe that humankind was making progress. Fragments of this turn-of-the-last-century worldview still remain, and I would suggest that atheist free-thinkers are at least cousins to the liberal theologians.
Liberation theology grew from the indigenous populations of Latin America formed into base communities who, through their study of the Bible, were formed by the Exodus story of Moses freeing the slaves from Egypt. From this, liberation theologians believe that God has a preferential option for the poor. Even in the New Testament true religion is defined as the way one treats the least, the last, the lost, and more specifically, the widows and the orphans. From this belief, communities formed by liberation theology exist to "comfort the afflicted and afflict the comfortable". Liberation theology is found also among African Americans, Koreans, Feminists and other groups drawn to the challenge that the worldview offers to the status quo. The Roman Catholic Church has actively sought to quash these base communities because as they sought to challenge the powers-that-be they often became tied to rebel groups influenced by Communism
