As Simone de Beauvoir points out in her introduction to The Second Sex, a prayer often voiced by orthodox Jewish males begins "Blessed be God . . . that He did not make me a woman." St. Thomas Aquinas, as Beauvoir notes, one of Christianity's most influential theologians and philosophers, argued that women were simply "'imperfect men.'" Beauvoir's point here is that the institution of religion, a creation of men, generally holds women to be inferior to men both intellectually and morally, a view, unfortunately, that has been moderated, but not eradicated, by centuries of experience and understanding that should have ended an artificial distinction created by a Judeo-Christian belief-system that fails to yield to reason and logic.
From a philosophical standpoint, women have also been victimized by belief systems created by males who voiced the coventional belief that women were not quite men in terms of intellect and morality. Again, as Beauvoir notes, even a first-rate thinker like Aristotle could not envision women as like men, but with different plumbing:
'The female is female by virtue of a certain lack of qualities . . . we should regard the female nature as afflicted with a natural defectiveness.'
The greatest philosopher of his time, then, essentially argues that women are different from men because they lack crucial attributes that render women defective versions of men.
In the eighteenth-century, according to Beauvoir, certain philosopers--Diderot, for example, "strove to show that woman is, like man, a human being, but she also notes that these philosophers were unique for their time and ultimately failed to convince their societies of a natural equality between men and women.
Ultimately, Beauvoir concludes that religion and philosophy have generally been either unsuccessful or instrumental in perpetuating the belief that women are not, and can never be, equal to men.