Section Two of the Catechism lists each commandment and how it relates to our Catholic faith. The article "The Third Commandment" was in the first section titled, "You Shall Love the Lord Your God With All Your Heart, and With All Your Soul, and With All Your Mind."
Remember the sabbath day, to keep it holy. Six days you shall labor, and do all your work; but the seventh day is a sabbath to the Lord your God; in it you shall not do any work. 90
The sabbath was made for man, not man for the sabbath; so the Son of Man is lord even of the sabbath. 91
(90: Ex 20:8-10; cf. Deut 5:12-15, 91: Mk 2:27-28)
Within the Catholic Church, Sunday is called "The Lord's Day." However, within it is still the core purpose of what the Sabbath was created to do -- mainly, to allow God's creation, man and woman, a day of rest from their labors.
Within Mosaic Law, there were strict regulations of what Jews could and could not do on the Sabbath. Today there are still strict rules and rabbinical debates, discussions, and consultations over what is permissible on the Sabbath and what is not.
However, "For the law was given through Moses; grace and truth came through Jesus Christ." (John 1:17 RSV) As Christians, we are no longer under the Law, as St. Paul said in his letter to the Romans (emphasis mine):
Now we know that whatever the law says it speaks to those who are under the law, so that every mouth may be stopped, and the whole world may be held accountable to God. For no human being will be justified in his sight by works of the law, since through the law comes knowledge of sin. But now the righteousness of God has been manifested apart from law, although the law and the prophets bear witness to it, the righteousness of God through faith in Jesus Christ for all who believe. For there is no distinction; since all have sinned and fall short of the glory of God, they are justified by his grace as a gift, through the redemption which is in Christ Jesus, whom God put forward as an expiation by his blood, to be received by faith. This was to show God's righteousness, because in his divine forbearance he had passed over former sins; it was to prove at the present time that he himself is righteous and that he justifies him who has faith in Jesus. (Romans 3:19-26)
The Catholic Church considers Sunday attendance at Mass as a fulfillment of the Sabbath. I knew we were were obligated to attend Mass every Sunday, but for whatever reason, I never associated it with the Sabbath. I just thought the Church wanted to make sure we didn't go astray because once you start skipping Mass, it's all too easy to allow sin to enter into your life without even realizing it. (And to be certain, the Church does want to make sure that doesn't happen.)
But I was surprised to find this (II The Lord's Day):
Sunday - fulfillment of the sabbath
2175 Sunday is expressly distinguished from the sabbath which it follows chronologically every week; for Christians its ceremonial observance replaces that of the sabbath. In Christ's Passover, Sunday fulfills the spiritual truth of the Jewish sabbath and announces man's eternal rest in God. For worship under the Law prepared for the mystery of Christ, and what was done there prefigured some aspects of Christ: 107
Those who lived according to the old order of things have come to a new hope, no longer keeping the sabbath, but the Lord's Day, in which our life is blessed by him and by his death. 108
2176 The celebration of Sunday observes the moral commandment inscribed by nature in the human heart to render to God an outward, visible, public, and regular worship "as a sign of his universal beneficence to all."109 Sunday worship fulfills the moral command of the Old Covenant, taking up its rhythm and spirit in the weekly celebration of the Creator and Redeemer of his people.(107: Cf. 1 Cor 10:11, 108: St. Ignatius of Antioch, Ad Magn. 9, 1: SCh 10, 88)
So attending Mass is to "render to God and outward, visible, public, and regular worship" as a sign of God's goodness, kindness, and love toward all mankind. In other words, it is a powerful reminder to the world that God exists and loves mankind.
From another perspective, honoring the Lord's Day is a way to preach the Good News to the world that God is worthy of honor and worship. It is a sign that although everyone is busy the other six days of the week, believers in God and His Son take one day a week to pause and remember the goodness of God, reflecting His action and inaction when He created the world in six days and rested on the seventh.
The Catechism continues to instruct us on how to treat the Lord's Day:
2184 Just as God "rested on the seventh day from all his work which he had done,"121 human life has a rhythm of work and rest. the institution of the Lord's Day helps everyone enjoy adequate rest and leisure to cultivate their familial, cultural, social, and religious lives.122
2185 On Sundays and other holy days of obligation, the faithful are to refrain from engaging in work or activities that hinder the worship owed to God, the joy proper to the Lord's Day, the performance of the works of mercy, and the appropriate relaxation of mind and body.123 Family needs or important social service can legitimately excuse from the obligation of Sunday rest. the faithful should see to it that legitimate excuses do not lead to habits prejudicial to religion, family life, and health.(121: Gen 2:2, 122: Cf. GS 67 # 3, 123: Cf. CIC, can. 120.)
Although Catholics do not have the strict guidelines of Jewish people, we are still expected to treat Sunday differently, refraining from work or activity that hinders the worship owed to God. It would seem there is latitude given to us as Catholics regarding what work or activities would "hinder" this worship. Personally, I know that after spending some time in thought and prayer, I realized I had been mowing through Sunday as though it was Saturday -- which caused me to question how was I honoring the Sabbath? Was I taking the time to properly honor God on this day? Or was I only giving Him a cursory nod of recognition for one hour during a Sunday Mass before heading off to do what I normally do the rest of the week?
Whatever you do, consider prayerfully what you do. I know for me, I am taking time to unplug from the Internet and spend the day reading and reconnecting with family and friends. I also prepared my home so that on Sunday, my time isn't taken up with laundry, cleaning, and cooking. For me, this ensures that I gain the benefits of fully resting, and yes, it has made a difference. I believe God knew how crazy our lives would become with all the obligations we would have, the responsibilities, and the demands on our time. Giving us one day to rest is a gift to us, helping us not only to recharge our batteries to but to re-invigorate our relationship with Him.
This section in the Catechism is well-worth reading and studying. I know there have been so many times in my life when I have felt fragmented; pulled in so many directions that I didn't know which end was up. And tired? When I push myself to do more and more and more, my natural bodily defenses wear down and lo and behold, I get sick. Or miss important events. Or forget important things. The list could go on.
My intention in writing about the Sabbath was not to claim that Christians were to honor the Sabbath in exactly the same way as Jewish communities (who are, for instance, forbidden to drive on the Sabbath), but to revisit this commandment and ask: what does it mean for me? How can I as a Catholic live out this commandment in a way that fulfills what God has intended?
There are many ways to honor the Sabbath, or the Lord's Day. I think what is important is simply that we take the time to inquire what that may entail.