Broadly, theology is the study of religion. However, this study can take many forms. If your goal is to work as a pastor, priest, rabbi or other religious authority figure, you may wish to pursue a degree focusing on ministerial work by entering a seminary or studying for a degree in divinity studies. If instead you want to study religions from an academic perspective, you may choose to earn a degree in comparative religions or on a specific religious subject.
Many colleges offer undergraduate degrees in religious studies, which typically focus on comparative religion, a program that requires study of different types of religious beliefs including Christianity, Islam and Hinduism. These programs also often focus on the differences and similarities between religions. Some schools also offer programs on specific religious traditions such as Yale University's major in Judaic studies.
If you want to study theology academically on the postgraduate level, you have many options. Many schools offer multiple academic degrees that focus on knowledge and research of contemporary or historical religious practices and philosophy rather than pastoral work. Universities typically offer a master's or doctorate in theology, although they may offer programs that are more specific as well, such as the University of Virginia's Ph.D. in Islamic studies.
For students interested in actively working as a religious leader or in another ministerial function, the most common degree is a master's or doctorate in divinity. Many Protestant Christian denominations as well as the Roman Catholic Church require pastors or priests to have completed at least a master's in divinity. This master's program can be much more intensive than a typical master's program; for example, Harvard University offers a master's in divinity program that requires three years of full-time study of religious history, theological philosophy and scriptural interpretation in addition to the four years needed for a bachelor's degree.
If you aspire to be a priest, rabbi or other religious leader, consider joining a seminary. These programs may incorporate religious and philosophical studies into a larger program. For example, the Jesuit order of Catholic priests sends its new initiates to complete master of divinity degrees after finishing a two-year novitiate program. After they earn this degree, they embark on a further series of non-academic pursuits including community service and work in Jesuit secondary schools, as part of their training.