What is the study of God's nature and religious truth?

Not a simple question since it involves how we are able, if at all, to access those things which can not be directly discerned using normal physical tools or sensibilities, and things which may be approached using several different intellectual techniques. If ultimate realities are indeed only subjective and personal in nature, then the rules of logic and reason do not necessarily apply, no propositional conclusions can be derived, verifiability and falsifiability are not a requirement, and philosophical incoherence is not a fatal flaw! On the other hand, if the ability of the human mind to formulate and organize conceptual principles is an indication that the universe at large, of which that mind is a part, innately contains real and comprehensible order and principle, then rationality and the laws of logic can form a basis for the following meaningful investigative techniques: The academically recognized category known as "Theology Proper" is concerned with evaluating what can be known of God as based on historical tradition or documents (such as The Bible) which purport to relay to humankind His own revelations about Himself. More generally and philosophically, "Ontology" is the study of basic reality or ultimate "being-ness", attempting to discover and define its nature, knowable properties, and its relational manifestation in the material world. What is classically known as the "Ontological Argument" is a formal proposition positing the existence of God as based on evidences taken from the nature of being, a subject wrestled with by Plato, Aristotle, St. Augustine, St. Anselm, and many others down through history. The study of knowledge itself is called "Epistemology", systematically dealing with how we can know anything, what methods apply to the discovery of that knowledge, how the validity of that which is knowable is determined, and what if any are its limitations. The broad title of "Metaphysics" by definition encompasses all that can be studied or known of that which is beyond or above the realm of the purely physical universe, thus including as subcategories both disciplines of ontology and epistemology.