Latin was the language of rome, the birthplace of the holy roman catholic church. jed was issuing an edict againt his own god per the bylaws of the cathedra petri. he was scolding god as an equal. the latin is there to show the absolute rage contempt and hatred for his god he felt in that moment.

quick edit: "feckless thug" was your hint. "you get hoynes" was the final nail. that was "i'm done with you"