Refers to cases where activism and pride in relation to an ideology have become excessive to the point of being harmful to others, oneself, and one's own cause. Particular aspects can focus on religion, politics, but can also apply to any other area where partisanship and its related dogma are fostered and encouraged. A zealous person is called a zealot.

While "excess of zeal" may be used to refer to very common and individual instances of excess, "zealotry" tends to be reserved for cases where excess zeal is shared with others, and has formed or merged with a dogma; typically with ideological self-perpetuation as among its primary foundations. The espoused use of force and violence to propagate the ideology, is a common characteristic of this self-perpetuation; perhaps inline with the "ends justify the means " rationale.