If there were no Mass, there could be no Catholic Church. The Mass is our act of worship, an act which we know to be worship really worthy of God, because it is the sacrifice of God's own Son. It is not just the feeble offering of our hands, but an act which we know does God supreme honor. God is adored adequately, God is thanked adequately. God is petitioned irresistibly for those things which His children need.
Perfect atonement is made for sin.