Heb 4:1-5,11; Ps 78 Do not forget the works of the Lord; Mark 2:1-12
"Let us be on guard while the promise of entering into his rest remains...for we who believed enter into that rest...And God rested on the seventh day from all his works...Therefore let us strive to enter into that rest, so that no one may fall after the same example of disobedience.."
We continue to follow the Letter to the Hebrews. Once again, we are invited to reflect on the disobedience of the Israelites as that which kept them from entering the promised Land, the symbol of the rest of God.
We are also asked to reflect on Exdus 20:8-11, where the Israelites are invited to unite themselves to God weekly on the Sabbath and ultimately in the attainment of salvation (Rev 14:13, CCC 345).
We are reminded that God does not rest from his work because he is tired or exhausted or in need of a break but rather he rest to show us our need to live and work for the "rest" that lies ahead or for the "rest" of our lives.
The Sabbath rest was meant to help us keep our top priority in the top place of our life. The "rest" kept everything in its right perspective and right order. The sabbath rest helped to reorganize our life just in case we began to think temporal things were more important than eternal matters.
Perhaps this is why we are told in chapter 13 in the Letter to the Hebrew that we should not neglect the Holy Assembly.
There is an old axiom that says the last in execution was the first in intention. at least according to St Thomas Aquinas. Whatever is done last was intended first. God creates the world looking forward to the day of rest so that he might instill in us what is most important of all. The sabbath rest points to worship and union with God. And it is in imitating God we enter into communion with him. All of creation is ordered to worship and adoration of God.
If we get that right then the rest of our life falls in harmony with the Divine will. For us as Christians, the eight day marks a day of new creation. The seventh day was a completion of the first creation, but the resurrection of Jesus marks a new creation for humanity and the world. The first creation finds its meaning in the new creation. The last in execution is the first in intention. This is why the Sabbath for us is on Sunday not Saturday. This of course directs us to the "final rest" that awaits us. It is in the culmination of history, that we find our truest purpose and rediscover the meaning of life, which is to be with God forever. As the Baltimore Catechism teaches us, "to know him, to love him, to serve him, and to be with him forever in heaven."
This is the rest we should strive after daily in our goings and comings.
Sunday Celebration is essential to true Christian living because it puts things in its proper place. It helps eternal matters first and foremost.
Hopefully this helps answer the question I get so often, "why should I go to Sunday worship?" "Why should I go to Mass?" We go because we keep temporal and eternal matters straight in our hearts and mind. We let our ultimate end give direction to our daily life. And we allow the Sunday rest to connect us to the heavenly rest that is our end. We imitate Christ who said "do this in memory of me." We reconnect to the new creation that directs to our ultimate union with God, which promise a new heaven and new earth.
We keep the end in mind then it where change how we get there and whether we arrive or not.