Source : Webster's Revised Unabridged Dictionary (1913)

Angelology \An`gel*ol"o*gy\, n. [L. angelus, Gr. ? + -logy.]
   A discourse on angels, or a body of doctrines in regard to
   angels.

         The same mythology commanded the general consent; the
         same angelology, demonology.             --Milman.

Source : WordNet®

angelology
     n : the branch of theology that is concerned with angels