ideologue

This term carries a strong negative connotation when describing someone who prioritizes theoretical purity over practical reality. It suggests a level of stubbornness or blindness to nuance, often implying that the person is more interested in the internal logic of their belief system than in the actual outcomes of their actions. In a more neutral or historical sense, it refers to the architects of political or social theories. However, in modern political discourse, it is almost exclusively used as a pejorative to describe a zealot or a dogmatist who refuses to compromise.