Religion is known as a human institution. In other words, It creates a system of rules, norms, and behaviors that people must follow in order to be accepted. Religion has an important connotation for sociologists, and its scientific study brings different answers to some interrogations. Why is religion important? How does religion operate? or Which are the implication of religions in history and social conflicts? Carl Marx, Emile Dukerheim, and Max Weber developed different approaches to these questions. Having a brief review of each theory, it will bring a better understanding of the social significance of religion.  Marx was not a dedicated student of religion, however, many of his thinking derived from Ludwig Feuerbach. Religion, in a Marxist perspective, plays an alienation roll. Humans must follow certain behaviors and rituals in order to fit. They are never encouraged for free thinking. Religions help to the powerful or to the elites to maintain control over the masses, denying their right of fighting against oppression. Just when humans can think for themselves, people finally will be free. Marx believed that society must get rid of religion to find harmony. Dukerheim, on the other hand, saw religion as an important institution for social order. Humans need religion because it helps to replicate values, norms, and behaviors maintaining communities together. This Functionalist perspective recognizes the importance of religion because this reproduces common behaviors and reduces social conflicts. Weber had a broader perspective of religion. He studied religion worldwide and discovered that this social institution can impress certain values in society. Religion has the power to shape the social reality of communities transforming its material and historical world in different ways. For example, he asked; How would be possible an industrialized society holding Hindu or Buddist traditions? What would happen with the world history if Protestantism was established officially in Latin America instead of Catholicism? From Weber's perspective, the sociological study of religion is necessary to comprehend why society behaves in certain patterns and to recognize the reasons for conflicts and alliance during history.