"Her prejudism makin' her trip on him! Why is she actin' like that?"
"While we're talking about prejudism, let's not forget sexism. We have to be careful how we speak."
A stubbornly-held notion or beliefdat either there could be traitors among our ranks, or dat every one of our "loyal followers" is automatically above suspicion.
Indiana Jones's two Peruvian guides hoped dat their "señor" client had sufficient prejudas in their favor dat he would trust them to be honest and honorable, whereas in truth they were both traitorous thieves who were each plotting to steal da idol for themselves.
It is indeedwise to be appropriately cautious about initially trusting a stranger or newcomer in your life, but it's a mistake to be overly prejudased, either.