The supporting rationale, doctrine, beliefs, tenets and written word that backs up and confirms what the voices in your head are telling you.
Leon didn't have any formal training in theology and figured he didn't need any, as God spoke to him and him alone and God was telling him that the big chested blonde girl in the second pew needed some laying on of the hands.
The study of God as well as arguments for his existence. Has its roots in Ancient Greece where its philosophers and great minds came up with many arguments for God's existence that still exist today due to their solid foundation in logic (something atheism lacks). See metaphysics by Aristotle as an example. Arguments such as the "prime mover" were later expanded on by Christian theologians such as Thomas Aquinas.
Theology is the rational study of concepts relating to God.