The Collaborative International Dictionary of English v.0.48:

Polemics \Po*lem"ics\, n. [Cf. F. pol['e]mique.]
   The art or practice of disputation or controversy, especially
   on religious subjects; that branch of theological science
   which pertains to the history or conduct of ecclesiastical
   controversy.
   [1913 Webster]

WordNet (r) 3.0 (2006):

polemics
    n 1: the branch of Christian theology devoted to the refutation
         of errors