In about 370CE the African libertine Augustine decided (under the influence of his sainted -literally- mother Monica), finally, to convert to Roman Catholicism, giving up his concubine and his Manichieism simultaneously. As is usual for extreme converts he became the flaming torch of truth, burning heretics left and right, bishop of Hippo (Egypt) and Doctor of the Church.
The latter he earned for his writings, which included the City of God where he claimed that the Catholic faith was the divine analog of Rome the eternal city, which at the time was beginning to show some cracks in the seams; only the City of God was much, much better. As a Platonist, he believed that the world was not a worthy life goal, only the attainment of heaven was important. He developed the theme of original sin (what Adam did to the entire human race), and creating the theological backdrop for Christ's final sacrifice.
Augustine's philosophy of life held Europe in it's talons for over 1000 years. Augustine's ideas are epitomized in the villain of Eco's The Name of the Rose, to whom laughter was the greatest sin. For over 100 years everyone within the church's grasp was brought up from birth believing the only thing that was truely worth doing was: he who dies with the most grace wins. Achieving anything in this life was not worth the time.
The history of the world shows it. It's certainly not the only problem the world had, but it was one of them.