Yom Kippur 2017 Once per year, on the Day of Atonement, actually plural, Yom HaKippurim, the Cohen Gadol (High Priest) performed his most holy function: making atonement for the sin of an entire people. It was on this day that he was most recognizable as HaCohen HaMashiach, the “Anointed Priest”-a type of the coming Messiah-because of his role