Noun
Excessive enthusiasm, unreasoning zeal, or wild and extravagant notions, on any subject, especially religion; religious frenzy.
Source: Webster's dictionaryFrom fanaticism to barbarism is only one step. Denis Diderot
A celibate clergy is an especially good idea, because it tends to suppress any hereditary propensity toward fanaticism. Carl Sagan
Fanaticism consists of redoubling your effort when you have forgotten your aim. George Santayana
The closer a man approaches tragedy the more intense is his concentration of emotion upon the fixed point of his commitment, which is to say the closer he approaches what in life we call fanaticism. Arthur Miller
The interval between the decay of the old and the formation and establishment of the new constitutes a period of transition which must always necessarily be one of uncertainty, confusion, error, and wild and fierce fanaticism. John C. Calhoun
It took 200 years for the Crusaders to create [this] Muslim fanaticism. It was the exact imitation of Christian intolerance. Terry Jones