You've heard of an ideological "purity test" I assume. For example, Democrats have one where you have to support abortion or you may as well leave the party. A purity spiral where the tests get ever more rigorous, and ridiculous, and you end up leaving otherwise fellow travelers behind and sometimes making them opposition, like what the Jacobins did to the Girondins, who supported the French Revolution, but not support the complete leveling of society and the destruction of religion.