Use the adjective theological to describe things related to religious studies. If you major in religion in college, you can call yourself a theological scholar.
A theological university is often called a seminary, a school where all the students learn about some aspect of religion. Scholars use the word theology to describe a thoughtful and rational study of religious beliefs, ideas of God, the history of religion, and more. Some theological students become ministers or priests. The root word is Greek, theologia, "an account of the gods."