That's the short version. But since I am never succinct when verbosity will do...
From Rebecca Traister's Hey, Obama boys: Back off already! (emphasis and bracketed edit mine):
One of my closest girlfriends, an Obama voter, told me of a drink she'd had with a politically [faux]gressive man who made a series of legitimate complaints about Clinton's policies before adding that when he hears the senator's voice, he's overcome by an urge to punch her in the face.That's a visceral and violent reaction to something that is specifically feminine.* And as long as there are men, who would ostensibly be part of the "humanist" movement, yet retain a visceral and violent reaction to the feminine, there is no foundation for a sexless, "humanist" movement.
Generally, those arguing in favor of a "humanist" movement won't say they're arguing for men's inclusion, instead citing what they perceive as the limitations of feminism/womanism—"But what about gay people or people of color or the disabled or the poor or…?" they ask, as if there is something intrinsic to feminism that precludes also fighting other biases. The truth is, if one is genuinely concerned with the betterment of women, one is necessarily concerned with fighting biases against any marginalized group, because, half (give or take) of all such groups are women.
When I advocate for women, I advocate for all women: Black women, brown women, white women, tall women, short women, fat women, thin women, disabled women, abled women, old women, young women, women with children, childless women, healthy women, ill women, dwarf women, poor women, rich women, middle class women, employed women, unemployed women, immigrant women, women in other countries, English-speaking women, non-English-speaking women, progressive women, conservative women, women in unions, women in comas, straight women, lesbian women, bisexual women, trans women, powerful women, weak women, vegan woman, vegetarian women, meat-eating women, religious women, atheist women, agnostic women, educated women, uneducated women, women who have survived rape, women who want my advocacy, women who don't, and every other conceivable expression, intersectionality, and experience of womanhood that exists on the planet.
Arguing for a "humanist" movement, because feminism/womanism is too limited, is necessarily predicated on viewing "women" as a group separate from "people of color" as a group separate from "LGBTQ" as a group separate from "disabled" as a group separate from "poor" as a group separate from "fat" as a group separate from… It's a failure to respect both intersectionality and the breadth of experience among women, no less among all humans.
And what kind of success can a "humanist" movement have, when it doesn't even recognize something so fundamental about humankind?
* Spare me the imbecilic protestations that it's only about Hillary and not women generally; I've been called a cunt too many times by commenters just passing through on a link to know it's never just about any one woman.