Source : Webster's Revised Unabridged Dictionary (1913)

   2. Believing the thing alleged no to be true; disbelieving;
      especially, believing that Bible is not a divine
      revelation, or that Christ was not a divine or a
      supernatural person. ``Unbelieving Jews.'' --Acts xiv. 2.
      -- {Un`be*liev"ing*ly}, adv. -- -- {Un`be*liev"ing*ness},
      n.

Source : WordNet®

unbelievingly
     adv : in an incredulous manner; "the woman looked up at her
           incredulously" [syn: {incredulously}, {disbelievingly}]
           [ant: {credulously}, {credulously}]