Some churches used to rule entire nations based upon their religions and sometimes corruption. Scientists (typically astronomers) would find new truths about the universe that would defy the preachings of the churches. Science and religion have had serious clashes all throughout history.
One example is a story of a man named Bruno who was the first to present the idea (which he strongly believed in) that the universe was infinite. Although he was religious, Bruno held onto this belief for his entire life, which ended when the church burned him at the stake for his defiance. Nowadays with modern science, we know that Bruno was right all along, as our universe continues to infinitely expand.