The strength of beliefs in certain discretionary causes can give rise to excessive or extremist behaviour. People who do not agree with the movement's views are excluded, and even condemned, vilified or harmed.
Recent examples are the willingness of members of environmental organizations to engage in illegal, even criminal behaviour, such as entering high security military compounds, or to take great personal risk, such as chaining themselves to trees which are to be removed by heavy equipment, or placing themselves in rubber dinghys between whaling boats and whales. Another example is the murder in 1993 of a USA doctor who performed abortions by an anti-abortion activist.