The Collaborative International Dictionary of English v.0.48:

Unfaith \Un*faith"\, n.
   Absence or want of faith; faithlessness; distrust; unbelief.
   [R.]
   [1913 Webster]

         Faith and unfaith can ne'er be equal powers:
         Unfaith in aught is want of faith in all. --Tennyson.
   [1913 Webster]