Pan-denominational mass as that of today is not what they could afford in the last few millennia. You've led your people to the Promised Land during the Judgment of Fire, and now you are selected as the Highest Priest. Now you are holding the mass, and everybody around you considers you as the much-prophesied Messiah. They're all solemnly attending the mass. You now pray to the God that Xeloss be blessed with the opportunity to settle down in the Promised Land.