Tracing the origins of the world’s major religions, as well as examining their sacred texts and how their belief systems have changed and diversified over time, are all part of the study of theology. This should include Judaism, which, despite being one of the world’s smallest religions, is also the world’s oldest organized religion, dating back to 2,085 BC. Beliefs centered on the top four religions by number of adherents, including Christianity, Islam, Buddhism, and Hinduism, should be investigated as well. These four religions account for 80 percent of the world’s population as of 2011.
Because human views on the nature of God and mankind’s relationship to the universe can be so diverse, learning about the history of theology can be a difficult and time-consuming endeavor. As of 2011, there were approximately 20 major religious groups in the world with at least one million members each, but this number varies greatly when individual sects and smaller religions are considered. There are an estimated 34,000 different Christian groups, each with its own set of beliefs and values.
Because most major religions are ancient, a theology education must include a significant amount of general history study for the time periods and cultures from which religions arose. Islam has dominated the Middle East and Near East, as well as large portions of North Africa, since its founding by Mohammed in 610 AD. Hinduism dates back to 1,500 BC on the Indian subcontinent. Both Buddhism and Taoism have closely related historical origins, with Gautama Buddha laying the foundation for Buddhist beliefs in 560 BC and Lao Tzu’s Taoist teachings in around 550 BC. Both religions are widely practiced in China, Japan, and other Asian countries, and they have been influenced by their diverse cultures over the past 2,500 years.
There have been periods in the history of several theological movements when major offshoots of the primary religious group emerged. When learning about the history of theology, these tend to be defining moments in history that must be understood in the proper context. Martin Luther’s Protestant Reformation in 1517 AD, which resulted in the formation of hundreds of Christian sects, and the Sikh rebellion against Hindu polytheism in the 15th century are two examples.
Many religions have roots in ancient mythology and folklore, and these aspects of human culture have a strong, albeit sometimes hidden or subtle, influence on contemporary religious beliefs. The Shinto belief system, centered in Japan, is an excellent example of a widely practiced religion with roots in ancient folklore. Shintoism encompasses a wide range of moral values that govern everything from romantic relationships to the honoring of veterans through war memorials and ritualistic agricultural practices. In order to account for transformational changes in Japanese culture, such as when it went from being an isolated nation to having relations with the west in the mid-19th century, theology courses that include learning about Shinto beliefs in the history of theology must account for transformational changes in Japanese culture.
Theology’s history is in constant flux, and it is frequently influenced and defined by external events in human society. The history of theology has been influenced by advances in science and technology, medicine, the discovery of new lands, and the mingling of cultures throughout history. The history of theology has been transformed and rewritten as humanity has gained astronomical knowledge, or as the western and eastern cultures of Greece and Persia met, or as the Portuguese colonized Mexico.