Was crossed = was angered or was not obeyed

As an adjective, crossed means angry.

In this context, I think it means blocked, stopped, impeded, thwarted, obstructed. "If the deity has something planned, do not get in the way! Do not try to stop him!" It does not mean "angry." The word that means "angry" is just "cross," not "crossed." And it refers to mild anger. "Be careful, he is cross today" means he is annoyed or irritable. In this case, the deity is not merely "cross;" he is very angry, he is furious. In other words, "cross" can be an adjective meaning "annoyed." It can also be a transitive verb, "do not cross him" meaning "do not try to stop him." The subject is the person trying to stop somebody. The object is the person being stopped. In this case, it is used in the passive voice, with an object but not a subject: the deity usually did terrible things when he "was crossed."

it has two meanings in that sentence. cross = angry crossed = if he were to be betrayed. so the sentence means the Israelites know that if they disobeyed God​ (crossed him) = would be cross (angry)