The Collaborative International Dictionary of English v.0.48:

unholy \un*ho"ly\ ([u^]n*h[=o]"l[y^]), a.
   Not holy; unhallowed; not consecrated; hence, profane;
   wicked; impious. -- un*ho"li*ly, adv. -- un*ho"li*ness,
   n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unholiness
    n 1: the quality of being unholy [ant: holiness, sanctitude,
         sanctity]

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "unholiness":
   godlessness, impiety, irreligion, profaneness, profanity,
   reprobation, sinfulness, un-Christliness, unangelicalness,
   unblessedness, unchristianliness, ungodliness, unhallowedness,
   unregenerateness, unrighteousness, unsacredness, unsaintliness,
   unsanctitude, unsanctity, wickedness