Christians do not keep the Jewish Sabbath. But the roots of the Torah are found in God’s liberating act of the Exodus. God cares for us, liberates and saves us. This suggests, invites, beckons a response on the part of those who claim to follow God
Saint John Paul describes it as a “duty.” And this is a good approach for us:
62. It is the duty of Christians therefore to remember that, although the practices of the Jewish Sabbath are gone, surpassed as they are by the “fulfilment” which Sunday brings, the underlying reasons for keeping “the Lord’s Day” holy — inscribed solemnly in the Ten Commandments — remain valid, though they need to be reinterpreted in the light of the theology and spirituality of Sunday: “Remember the Sabbath day to keep it holy, as the Lord your God commanded you. Six days you shall labor, and do all your work; but the seventh day is a Sabbath to the Lord your God. Then you shall do no work, you, or your son, or your daughter, or your servant, or your maid, or your ox, or your ass, or any of your beasts, or the foreigner within your gates, that your servant and maid may rest as well as you. You shall remember that you were a servant in the land of Egypt, and the Lord your God brought you out from there with a mighty hand and an outstretched arm. Therefore the Lord your God commanded that you keep the Sabbath day” (Dt 5:12-15). Here the Sabbath observance is closely linked with the liberation which God accomplished for his people.
The Holy Father has suggested in previous sections that the Exodus Ten Commandments are linked to the Creation, and that those cited above in DD 62 are connected to the liberation from Pharoah’s slavery.
Keeping a Sabbath seems like a rather arbitrary rule. I think we’d need to go a bit deeper than viewing Sabbath-keeping as a mere rule. The suggestion in Deuteronomy 5 is that it serves as a continuation of our deliverance into freedom. We ignore Sunday at our own risk.