"Holy Crusade" refers to a religiously-driven military campaign. Some synonyms for this expression include "divine mission," "sacred war," and "pious expedition." Another synonym that could be used in the context of politics or social activism is "moral crusade," which denotes a fervent and passionate pursuit of a particular cause considered righteous or virtuous. In some cases, "jihad" might also be considered a synonym for "holy crusade," although it typically connotes a more specific Islamic concept of struggle or striving. Regardless of the terminology employed, the underlying idea is usually one of collective action, motivated by a sense of spiritual or ethical imperative to achieve a higher goal or purpose.