[1] : The Collaborative International Dictionary of English v.0.48

unbelieving \un`believ"ing\, a.
   1. not believing; incredulous; doubting; distrusting;
      skeptical.
      1913 webster
      1913 webster

   2. believing that the thing alleged is not true;
      disbelieving; especially, believing that the bible is not
      a divine revelation, or that christ was not a divine or a
      supernatural person. "unbelieving jews." --acts xiv. 2.
      1913 webster -- un`believ"ingly, adv. --
      un`believ"ingness, n.
      1913 webster
see also:
un`believ"ingly un`believ"ingness 

[2] : WordNet (r) 2.0

unbelievingly
     adv : in an incredulous manner; "the woman looked up at her
           incredulously" syn: incredulously, disbelievingly
           ant: credulously, credulously
see also:
incredulously disbelievingly credulously 

Unbelievingly >> U Words
Unbelievingly, definition of term: Unbelievingly
unbelievingly_pag1.html