Although the third commandment says that God created the world in six “days” and after seeing that it was good, he blessed the seventh day, Saturday, and that day He rested. (Genesis 2:1-3), why do we go to mass on Sunday? The Church, by a tradition handed down from the apostles, celebrates the Paschal Mystery on the first day (CCC 1166), Sunday; the same day of resurrection of our Lord. Because just as God started creation on the first day with “Let there be light…” (Genesis 1:3) and rested on the seventh day, Jesus Christ rests on the Saturday in the tomb and starts our redemption and salvation also the first day, since He is the light of the world (John 8:12) who comes to enlighten us so that we do not walk in the darkness that is sin.
Just as God rested and contemplated his work, seeing that it was good and blessed that day, we, by our call to holiness (Matthew 5:48), must bless Sunday, contemplate if our works have been good; and feed on the word of God, as well as the body and blood of our Lord to be able to be received at the end of times in the place in heaven that our Lord Jesus Christ has prepared for us (John 14:2).
So, let us come to Mass with joy, for the Lord awaits us with the prepared banquet that gives us eternal life; Mass not only begins when the priest enters the temple in procession, but also when each of us begins to get ready to attend the sacred meal on pilgrimage to the temple, because just as God brought the Israelites out of Egypt (Exodus 20: 2) towards the promised land, Jesus Christ takes us out of the darkness of sin towards eternal life with Him, because we are God’s chosen people by virtue of the new covenant in Jesus Christ (1 Peter 2:10, JPII Gen. Aud. Nov 6, 1991—1)