This article aims to better understand current opposition to feminist politics by analyzing positions of extreme-right populist parties on gender knowledge, "explicit and implicit representations concerning the differences between the sexes and the relations between them, the origins and normative significance of these, the rationale and evidence underpinning them and their material form" (Cavaghan, 2017, p. 48). These understandings contribute to constructing a societal truth on gender and/or to setting the terms of the political debate about gender issues. This article introduces and uses the theoretical concept of episteme to highlight the systematic nature of discursive institutional settings, and the role knowledge and truth production plays in processes reproducing or countering gender inequality. The article analyzes the positions of extreme-right populist parties in the Netherlands and their discursive attacks on the feminist project in the Netherlands, in which these opponents use a redefined concept of 'cultural Marxism'. Through this analysis, the article illustrates the theoretical argument that epistemic dynamics play a strong role in opposition to feminist politics, that the shifting epistemic framing of science is important in these oppositions and that more comprehensive attention for the epistemic dimension is needed.