The Collaborative International Dictionary of English v.0.48:

Freethinker \Free"think`er\, n.
   One who speculates or forms opinions independently of the
   authority of others; esp., in the sphere or religion, one who
   forms opinions independently of the authority of revelation
   or of the church; an unbeliever; -- a term assumed by deists
   and skeptics in the eighteenth century.
   [1913 Webster]

         Atheist is an old-fashioned word: I'm a freethinker,
         child.                                   --Addison.

   Syn: Infidel; skeptic; unbeliever. See Infidel.
        [1913 Webster]

WordNet (r) 3.0 (2006):

freethinker
    n 1: a person who believes that God created the universe and
         then abandoned it [syn: deist, freethinker]