Wiktionary's second definition of "militant": Aggressively supporting of a political or social cause; adamant, combative. [from 17th c.] That seems entirely a

Wiktionary's second definition of "militant": Aggressively supporting of a political or social cause; adamant, combative. [from 17th c.] That seems entirely apt to me. It's a metaphorical usage, rather than a literal one, but it has been used that way for centuries. https://en.wiktionary.org/wiki/militant https://en.wiktionary.org/wiki/militant