As a social institution, religion is an organized structure of behaviors and social interactions that addresses the spiritual needs of society.

Religion is a system of beliefs that affects how people make sense of their experiences and provides a framework for questions about life, death, and the purpose of existence. Religiosity is the extent to which religion is important to an individual or community.

There is a multitude of religions worldwide. Currently, the most practiced religions are Christianity, Islam, Hinduism, and Buddhism. Religions that espouse the existence of one god are monotheistic, while those that express belief in many gods are polytheistic. 

Three major types of religious organization can be described based on how fully they are integrated into society at large:

• A church is a religious organization that is well established in the larger society.
• A sect is a more radical group that forms by breaking away from the established norms or beliefs of a mainstream church.
• A cult has views or practices that situation it outside the traditions of mainstream society and, unlike a sect, tends to form outside of any pre-existing religion.

These organizations exist on a continuum. After growing over time, a cult or sect may eventually become more mainstream and transition into a church. Cults and sects are likely to have living founders, but by the time religious organizations become churches, they have typically gone through several generations of leadership. Remember, the words cult and church are used differently in sociology than in everyday language. A church can mean any mainstream religion and is not necessarily associated with Christianity. A cult is not defined by extreme practices like brainwashing.

Since society and religion are interrelated, there is an important relationship between religion and social change. Modernization has made it possible for individuals to access information about many types of religions practice, especially through the internet. As a result, people are exposed to diverse challenged to their religious identities. It is much easier now than it was in the past for religious ideas to spread across the globe. Religion has also been affected by secularization, or decreasing devotion to religious doctrines or practices. Fundamentalism is the opposite tendency, which entails a strictly literal interpretation of sacred writings. A limited tolerance for other religions often accompanies this ideology.