RPG Information (FFG) Edit
Theology was a Scholar Skill which covers knowledge of religious philosophy, doctrine, and practice, including the kami, the Fortunes, the powers and deities associated with Shinseism and other religious traditions, as well as to perform supplications to these powers. A character versed in Theology is also versed in religious history and associated knowledge, including astronomy and the related fields of metaphysics and science with mystical implications such as Ancestor Worship, Divination, Fortunism, Invocation, and Mahō. 
RPG Information (AEG) Edit
Theology is the skill of those characters who are familiar with all the rites and practices of worshiping the many gods of Rokugan.  They also knew where many famous religious shrines were, and what the history of each Fortune was said to be.  It is considered a High  and Lore Skill.