Complex sentence: They posit that because of patriarchy, women have come to be viewed as the "other" to the male norm and as such have been systematically oppressed and marginalized; they furthermore assert that men as a class benefit from the oppression of women.
Split into simpler sentences: They posit that because of patriarchy, women have come to be viewed as the "other" to the male norm and as such have been systematically oppressed and marginalized. They furthermore assert that men as a class, benefit from the oppression of women.