Reformed Baptists affirm the binding nature of the Fourth Commandment (Remember the Sabbath day) while teaching that the Sabbath has been transferred from the seventh day to the first day of the week in light of Christ's resurrection. The 1689 London Baptist Confession, Chapter 22, teaches that the Sabbath was part of the moral law and remains binding on Christians, but the day itself has been changed. Sunday, the Lord's Day, is observed as the Christian Sabbath in commemoration of Christ's resurrection and the completion of redemption.

The moral principle of the Fourth Commandment — the consecration of one day in seven to the worship of God and rest from ordinary labor — is perpetually binding. The ceremonial aspects of Old Testament Sabbath observance (Levitical restrictions and temple rituals) are abrogated. Christians are not bound by Jewish Sabbath laws (no work, travel, or food preparation) but are called to dedicate the Lord's Day to worship, spiritual refreshment, and works of mercy.

The observance of the Christian Sabbath is shaped by the regulative principle of worship: worship practices must be commanded or derived from Scripture. Many Reformed Baptist congregations, influenced by the regulative principle, restrict their Sunday activities to worship, prayer, study, and works of mercy. Others permit reasonable rest and recreation. There is no legalism imposed on observance; the focus is on conscious dedication to God and his worship.