Partisan means biased in favor of a political party. Specifically, the OTHER political party — the one you like the least.
When you say something is partisan, you are saying you don’t like it and that anybody who does like it is just falling in line behind an authority figure or mindlessly fighting for the team they think they’re on. You are accusing them of not thinking.
Since most people aren’t thinking most of the time, the odds may be in your favor here. But those same odds apply to every single one of your extremely well considered positions. You’re just as likely as anyone else to be an intractable partisan ideologue, and the people you think are intractable partisan ideologues are just as likely as you to believe they are rational, reasonable, independent thinkers.
Would you ever call your own opinions partisan? Would anyone else?