Culture wars have two main functions. First, to split an existing, dominant social or political coalition apart by the clever use of wedge-issues. (Not all wedge-issues are a part of a culture war.) So, a culture war reveals a latent or induces real divergence in a pre-existing coalition. So, for example, how to think about trans-issues has split contemporary feminism apart (especially in the U.K, which is itself an interesting phenomenon). Second, and this mirrors the first function, to induce or solidify unity within a potentially heterogeneous coalition (think of the role of women’s ‘right to choose’ in America’s Democratic party). So, the issue must have salience to what we may call ‘tribe formation.’ (If you don’t like my examples offer your own!)
Now, the term ‘culture war’ is a literalist translation of the German ‘Kulturkampf.’ This nineteenth century conflict involved a major political conflict between Bismarck and the Catholic Church over control of educational institutions (and the content taught) as well as ecclesiastical appointments. In it national/ethnic stereotypes (about the Polish) were used to shift balance of allegiance. One reason I mention this origin of the term because in it we already see many of the later features of culture wars: the significance of education, especially the education of social elites, the role of non-materialist values, including ethnicity/race, religion, and nationalism.