But it's not difficult to find similarities. For instance, I have often noted that modern feminism wants to make gender (more exactly the fact of sex distinctions) not matter.
So too did Sarah Grimke. Here are some excerpts from a political letter she wrote in 1837 titled "Social Intercourse of the Sexes":
permit me to offer for your consideration, some views relative to the social intercourse of the sexes. Nearly the whole of this intercourse is, in my apprehension, derogatory to man and woman, as moral and intellectual beings. We approach each other, and mingle with each other, under the constant pressure of a feeling that we are of different sexes; and, instead of regarding each other only in the light of immortal creatures, the mind is fettered by the idea which is early and industriously infused into it, that we must never forget the distinction between male and female. Hence our intercourse, instead of being elevated and refined, is generally calculated to excite and keep alive the lowest propensities of our nature. Nothing, I believe, has tended more to destroy the true dignity of woman, than the fact that she is approached by man in the character of a female.
... Until our intercourse is purified by the forgetfulness of sex, - until we rise above the present low and sordid views which entwine themselves around our social and domestic interchange of sentiments and feelings, we never can derive that benefit from each other's society which it is the design of our Creator that we should. Man has inflicted an unspeakable injury upon woman, by holding up to her view her animal nature, and placing in the back ground her moral and intellectual being.
In the same letter she describes her ideal woman as follows,
... Such a woman feels, when she enters upon the marriage relation, that God designed that relation not to debase her to a level with the animal creation, but to increase the happiness and dignity of his creatures ... She views herself, and teaches her children to regard themselves as moral beings; and in all their intercourse with their fellow men, to lose the animal nature of man and woman, in the recognition of that immortal mind wherewith Jehovah has blessed and enriched them.
She uses very similar language to that of modern liberals, describing sex distinctions as a "fetter" and wanting us to learn to be "forgetful" of them.
She is not less radical than modern feminists. She believes the recognition of sex distinctions to be "low" and "sordid" and "debased" and considers our manhood and womanhood to be part of a merely animal nature as opposed to a purified spiritual nature in which we would not be conscious of being man or woman.
I think she has it wrong. We do not add to our spirituality by stripping away our identity as men and women. It might be true that there are certain aspects of an "animal" existence that are connected to being male and female. But so too are there aspects of an "animal" existence that are common to the sexes (e.g. eating, digestion etc). We don't suddenly live on some sort of ethereal plane if we think of ourselves as desexed creatures.
And there do exist more spiritual aspects of our embodiment as men and women. The highest order one is our perception of a masculine and feminine essence which is realised to a greater or lesser extent in the behaviour or qualities of individual men and women. Another is the highly gendered nature of heterosexual love which is experienced not just as the love of a particular personality or intellect (in which case we might just as easily love someone of our own sex), but of a sense of a complementary union between the masculine and feminine. There is also the experience of maternal love and paternal love, which are part of a gendered dynamic of relationships within the family. Our sense of duty and virtue, too, is at least partly connected to our distinct existence as men and women (e.g. although courage exists as a virtue for both men and women, we do connect it in specific ways to masculinity).
Where does Sarah Grimke's argument leave people? If we can't act as men and women, then how are we supposed to act?
Sarah Grimke wrote a lot about following our "moral being". But this appears to have a largely modern meaning. We are to be "ennobled" by pursuing "moral causes". And these causes are aimed at achieving equal autonomy.
I write this because I suspect that Sarah Grimke's Quakerism was tending already, even in the 1830s, more toward a secular modernity (based on liberal political activism) than Christian orthodoxy.