The Second London Baptist Confession speaks eloquently about the importance of the Sabbath Day

As it is a law of nature, applicable to all, that a proportion of time, determined by God, should be allocated for the worship of God, so, by His Word, He has particularly appointed one day in seven to be kept as a holy Sabbath to Himself. The commandment to this effect is positive, moral, and of perpetual application. It is binding upon all men in all ages. From the beginning of the world to the resurrection of Christ the Sabbath was the last day of the week, but when Christ's resurrection took place it was changed to the first day of the week, which is called the Lord's day. It is to be continued to the world's end as the Christian Sabbath, the observance of the seventh day being abolished.

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