the lunatic fringe
The most extreme members or portion of a larger group of people. The group has widely been dismissed as the lunatic fringe of the religion, taking its most fundamentalist aspects and warping them into a cult-like ideology based on prejudice and hate. They're part of some lunatic fringe who believe that eating anything that dwells or grows above ground pollutes the body with toxins.
the ˌlunatic ˈfringe(disapproving) members of an organization or group who are more extreme than the others; extreme groups: It’s the lunatic fringe of the Animal Liberation Front which smashes the windows of butchers’ shops, not ordinary members like us.The word lunatic means crazy. It comes from the Latin word luna, meaning ‘moon’, because people believed that the changes in the moon caused temporary madness.
lunatic fringe, the
A minority group who have what others consider very extreme beliefs. The term was first used (and perhaps coined) by Theodore Roosevelt in History as Literature (1913): “There is apt to be a lunatic fringe among the votaries of any forward movement.” At first used mainly for political extremists, the expression was later extended to other venues, as by Diana Ramsay in Deadly Discretion (1973): “Antique shops were magnets for the lunatic fringe.”
See also: lunatic