Source : Webster's Revised Unabridged Dictionary (1913)

Infidel \In"fi*del\, n.
   One who does not believe in the prevailing religious faith;
   especially, one who does not believe in the divine origin and
   authority of Christianity; a Mohammedan; a heathen; a
   freethinker.

   Note: Infidel is used by English writers to translate the
         equivalent word used Mohammedans in speaking of
         Christians and other disbelievers in Mohammedanism.

   Syn: {Infidel}, {Unbeliever}, {Freethinker}, {Deist},
        {Atheist}, {Sceptic}, {Agnostic}.

   Usage: An infidel, in common usage, is one who denies
          Christianity and the truth of the Scriptures. Some
          have endeavored to widen the sense of infidel so as to
          embrace atheism and every form of unbelief; but this
          use does not generally prevail. A freethinker is now
          only another name for an infidel. An unbeliever is not
          necessarily a disbeliever or infidel, because he may
          still be inquiring after evidence to satisfy his mind;
          the word, however, is more commonly used in the
          extreme sense. A deist believes in one God and a
          divine providence, but rejects revelation. An atheist
          denies the being of God. A sceptic is one whose faith
          in the credibility of evidence is weakened or
          destroyed, so that religion, to the same extent, has
          no practical hold on his mind. An agnostic remains in
          a state of suspended judgment, neither affirming nor
          denying the existence of a personal Deity.

Infidel \In"fi*del\, a. [L. infidelis; pref. in- not + fidelis
   faithful, fr. fides faith: cf. F. infid[`e]le. See
   {Fidelity}.]
   Not holding the faith; -- applied esp. to one who does not
   believe in the inspiration of the Scriptures, and the
   supernatural origin of Christianity.

         The infidel writer is a great enemy to society. --V.
                                                  Knox.

Source : WordNet®

infidel
     n : a person who does not acknowledge your God [syn: {heathen},
         {pagan}, {gentile}]