The fundamental reason for saying that sabbath observance is mandatory is the commandment, ‘Remember the sabbath day to keep it holy.’
‘Remember the sabbath day to keep it holy. Six days shalt thou labour and do all thy work; but the seventh day is the sabbath of the Lord thy God; in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates; for in six days the Lord made heaven and earth, the sea, and all that in them is, and rested the seventh day; wherefore the Lord blessed the sabbath day, and hallowed it.’ Exodus 20:8-11.
This includes (i) a principle, that one day in seven should be kept holy to the Lord, (ii) a requirement, to keep it holy by resting from the work which has to be done on the other six days, and (iii) some reasons for the requirement, in that God claims this day for his own, rested on it himself, and blessed it.
The reasons for celebrating the sabbath are amplified in other parts of scripture, so that today (ie in New Testament times) we not only have the work of creation to give thanks for, but also the memory of the ways that God’s people were delivered in the past (as in Deuteronomy 5 – ‘Remember that thou wast a servant in the land of Egypt, and the Lord thy God brought thee our thence through a mighty hand and by a stretched out arm; therefore the Lord thy God commanded thee to keep the sabbath day’) and much more especially for the fact that Christ has now risen from the dead, with all that that signifies.
Keeping the sabbath day holy now is a way of showing that you,
- recognise Christ’s lordship over this day (the Son of man is Lord of the sabbath, he said, just as Jehovah said the seventh day is the sabbath of the Lord thy God)
- believe that he rose again from the dead the third day, according to the scriptures, including the fact that his resurrection was earned by the success of the redemptive death that he died
- are looking forward to heaven, presented as a sabbath-style rest to be entered into by believers
- value the benefits made available for your spiritual welfare by the provision of a day when you don’t need to be busy with ordinary work-related things – when you can spend the time absorbing yourself instead in both communal and personal ways of worshipping God on his holy day
Because of how beneficial sabbath observance is to our spiritual lives, it’s a wonder that even Christian people sometimes find it so hard to obey this commandment. It is a commandment – so it’s only as, and yet every bit as, binding and/or restrictive as, say, the commandment ‘thou shalt not kill’ – but none of his commandments are grievous (in themselves, and neither should they be felt grievous by us), and this one in particular is so much more of an opportunity than a duty because of how kindly it makes provision for people’s spiritual and eternal wellbeing, as well as their physical and temporal wellbeing like all the rest of the commandments.