Source : Webster's Revised Unabridged Dictionary (1913)

Sectarianism \Sec*ta"ri*an*ism\, n.
   The quality or character of a sectarian; devotion to the
   interests of a party; excess of partisan or denominational
   zeal; adherence to a separate church organization.

Source : WordNet®

sectarianism
     n : a narrow-minded adherence to a particular sect or party or
         denomination; "he condemned religious sectarianism" [syn:
          {denominationalism}]