Fanaticism consists in redoubling your effort when you have forgotten your aim. George Santayana
Fanaticism in religion is the alliance of the passions she condemns with the dogmas she professes. Lord Acton
Fanaticism is overcompensation for doubt. Robertson Davies
From fanaticism to barbarism is only one step. Denis Diderot
Fanaticism obliterates the feelings of humanity. Edward Gibbon