a) What is the Third Commandment of God?
The Third Commandment of God is: Remember to keep holy the Lord’s Day.
We should go to Mass, have some time for rest, and avoid unnecessary work on Sundays and Holy days of obligation.
b) Why should an Altar Server know and live the Third Commandment?
The Sabbath day (Saturday) is the seventh day of creation, the day on which God rested. For us, Christians, Christ’s resurrection from the dead (which was on a Sunday, the first day of the week) marks the beginning of God’s new creation, and, as such, has become the new Sabbath day and the first among all the feasts. It was also on a Sunday, Pentecost, that the Holy Spirit descended upon the Church.
An Altar Server should encourage his family, friends, and classmates to attend Mass on Sundays and Holy days of obligation, and even daily if they can.