The Collaborative International Dictionary of English v.0.48:

Unquestioning \Unquestioning\
   See questioning.

WordNet (r) 3.0 (2006):

unquestioning
    adj 1: not inclined to ask questions
    2: being without doubt or reserve; "implicit trust" [syn:
       implicit, unquestioning]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "unquestioning":
   abiding, absolute, admitting no exception, all-out, categorical,
   clear, complete, conclusive, decided, decisive, definite,
   definitive, determinate, downright, enduring, entire, explicit,
   express, final, firm, fixed, flat, flat-out, global, implicit,
   inappealable, indisputable, never-failing, out-and-out, outright,
   peremptory, perfect, positive, round, steadfast, steady, straight,
   straight-out, total, uncircumscribed, unconditional, unconditioned,
   undoubting, unequivocal, unhampered, unhesitating, unlimited,
   unmistakable, unmitigated, unqualified, unreserved, unrestricted,
   unshakable, unshaken, unwaivable, utter, whole, without exception,
   without reserve