Feminism is the radical idea that women are people, and it receives a great deal of controversy because that one small idea implies that men can be wrong.
Not necessarily true. Feminism is an ideological movement that claims to hold the notion that “women are people”. It receives a great deal of controversy not because that one small idea implies that men can be wrong, but because a lot of the time it’s non-intersectional, dogmatic, and quite frankly sexist. Many of its campaigns, (the “1-in-4” program, for example) erase vast numbers of victims while indirectly sheltering their attackers. It also tends to have an extremely one-sided view of the current gender privilege situation.
But we can see why you didn’t pick that definition. Not pithy enough for a catchphrase.