Two examples of religious effects on the people of the world, which are from opposite ends of the spectrum. One is a good use of people's time and resources - aid to our fellow human beings and the other is the Holy Wars, which took place in approximately 1080 AD.
In the brutal era of wars that tore Europe apart in the closing days of the first millennium AD, no period was more confusing, or more tragic, than the nearly two hundred years Europe spent locked in bitter fighting in the Middle East. This era, known as the Age of Crusades, would lead to some of the most atrocious acts and miserable failures ever made in the name of religion. The story of the Crusades actually begins centuries before the First Crusade was launched in AD 1096. However, the Church had begun to develop with Rome as its center, and the churches of the East turned to Constantinople rather than the developing Papalcy in Rome.
The first Popes were warlike and power-hungry and they wanted the entire Christian world under their control. During the latter half of the first millennium AD, the teachings of Islam began to spread throughout North Africa and Asia Minor. The Popes of Rome, fearful that this new religion would displace them from their still-tenuous position, needed a way to suppress this new, peaceful religion coming out of the East.
Then, the final piece of the puzzle came into focus under the Western concept of primogeniture. The younger sons of European nobility, with no hope of ever ruling their family lands, became unruly as they sought to establish themselves, and began slaughtering each other. Rome, anxious to get these disruptive young nobles out of Europe, saw their chance to solve their problem. In AD...