Populism has gained significant attention recently, yet there is less understanding of strategies to confront it. This study focuses on the communication of these reactions by examining the populism/antipopulism divide created by populist parties’ challengers. Antipopulists present themselves as an antithesis of populism, offering an alternative to populism by constructing two identities: populist identity (“them”) and antipopulist identity (“us”). While antipopulism is argued to be depolarizing, based on civility, calmness, and knowledge, populism is portrayed as polarizing, using emotional and irrational language. However, we know little about the content of these identities and how these identities are presented stylistically. This study examines the content of the populism/antipopulism divide in the messages of antipopulist actors and their association with specific communication styles. Our study utilizes a quantitative content analysis of an original dataset of posts on Facebook and Instagram (n = 1291) before the 2021 elections in Czechia, along with an automated frequency analysis of antipopulists’ posts (n = 44,877) from September 2017 to December 2021. Our results suggest that the divide was increasingly present in the antipopulists’ messages, and it was associated with the strategic use of appeals to negativity, emotions, knowledge, and rationality. This indicates that even though antipopulists claim to have a rational and fact-based approach, the style of their communication reveals an emotional component, contributing to the overall level of polarization.