Working on Sunday is never called a sin in the Bible. This misconception has arisen based on a modern misunderstanding of the Old Testament's commands to rest on the Sabbath. In the Ten Commandments and elsewhere in the Law of Moses, the Israelites were commanded to do no work on the seventh day (Exodus 20:8-11). It was considered the day on which God rested (Genesis 2:1-3).
What does the Bible say about working on Sunday? Is it a sin?
There are two problems involved with the misconception of working on Sunday being sinful. First, the Sabbath day is Saturday, not Sunday. The seventh day in the Jewish calendar has always been Saturday. Sunday is the first day of the week in the Jewish calendar.
The idea of the Sunday as a time of Sabbath rest is based on the idea that Sunday became the holy day because this was the day of the resurrection of Jesus. In AD 321, Roman emperor Constantine decreed Sunday as a day of rest. Sabbatarianism became popular in the time of the English and Scottish Protestant reformations, especially in the teachings of John Knox. The Puritans who came to America popularized the idea, leading to many businesses being closed on Sundays even into modern times.
Today, some religious groups continue to practice the idea of keeping the Sabbath. The most well-known example is the Seventh-Day Adventists, who consider Saturday as the true Sabbath and a day during which all Christians should rest.
The second problem with calling Sunday the Sabbath is that practicing the Sabbath was part of the Mosaic Law, not a law for all time and all places. In fact, the apostle Paul dealt with this concern among early Christians, including many Christians who came from a Jewish background in which the Sabbath was part of life. He wrote in Romans 14:5-6: "One person esteems one day as better than another, while another esteems all days alike. Each one should be fully convinced in his own mind. The one who observes the day, observes it in honor of the Lord." Yet Paul also wrote, "For whatever does not proceed from faith is sin" (Romans 14:23).
The conclusion is that observing the Sabbath, either on the actual day (Saturday) or on Sunday, is perfectly acceptable, but is not a biblical command. If a person feels led to rest on Sunday to honor God, it is acceptable to do so based on their faith. Rather than judge one another in this area, believers are called to accept one another, realizing, "each of us will give an account of himself to God" (Romans 14:12).
What is the Sabbath? Is the Sabbath day for rest or for worship?
Is Sabbath-keeping something Christians should do?
Did Constantine change the Sabbath? Did Constantine make the Sabbath Sunday instead of Saturday?
Are Christians expected to obey the Old Testament law?
How can I know what is a sin and what isn't?
Truth about Sin