what do you call it when one is contentious?
I would call them contentious. But you must understand this is a judgement call. It would be an opinion. Where you might call me contentious, I would say that I earnestly contend. Like Paul and Jude who said we must “earnestly contend for the faith...once delivered to the saints” because “certain men [have] crept [into the church] unawares...ungodly men...denying...God, and...Christ” (2 Tm 3:8) (Jude 3-4).
Have you ever noticed that some folks are contentious about other folks' perceived contentiousness?