B - Philosophy
BF - Psychology
BJ - Ethics. Etiquette. Social Usage
BL - Religions. Mythology. Rationalism
BM - Judaism
BP - Islam. Bahaism. Theosophy, etc.
BQ - Buddhism
BR - Christianity
BS - The Bible
BT - Doctrinal Theology
BV-BX - Christian Denominations and Practices
These books can be found on the 2nd floor. At top of stairs, turn right and go past study rooms. At book stacks, the sections to your left contain religous studies books by call numbers above.
If you're looking for an overview of a particular religious concept or topic, reference sources such as encyclopedias and dictionaries are good places to start. Give these a try: