Definify.com
Webster 1913 Edition
Unbeliever
Unˊbe-liev′er
,Noun.
 1. 
One who does not believe; an incredulous person; a doubter; a skeptic. 
2. 
A disbeliever; especially, one who does not believe that the Bible is a divine revelation, and holds that Christ was neither a divine nor a supernatural person; an infidel; a freethinker. 
Syn. – See 
Infidel
. Webster 1828 Edition
Unbeliever
UNBELIE'VER
, n.1.
  An incredulous person; one who does not believe.2.
  An infidel; one who discredits revelation, or the mission, character and doctrines of Christ.  2Cor. 6.