Why Is a Week Seven Days?

Introduction

Have you ever wondered why our week is seven days long? Why seven? If you stop to think about it, the number seven is actually not a “natural” number we observe in our physical universe. So how come we don’t use a more natural (even) number like 10 (number of our fingers/toes) or 12 (number of months per year) or any other number for that matter? Since there are about 365 days in a year, why not just divvy up the year into something like 73 five-day week chunks?

All of our other usual time-markers (i.e., days, months, years) have an astronomical basis that we observe in our universe created by God. For instance, a day is defined by the time it takes the earth to rotate once on its axis. A month is the (approximate) time of the new moon cycles; a year is the time it takes the earth to complete one orbit around the sun, and the seasons are determined by the equinoxes and solstices (due to earth’s 23.5° tilt toward the sun). However, a week has no such natural basis!

Nonetheless, we all conduct our usual lives based on this standard seven-day week (i.e., we all do certain things on particular days of the week). The common schedule is to have five to six “working” days (the workweek) and one to two “resting” days (the weekend). But why do we, including Christians, Buddhists, and atheists, naturally follow this pattern? And where did this pattern even come from?

What Does the “World” Say?

What does the secular community think? Many secular historians have (somewhat superficially) attempted to explain the origin of our seven-day week in various manners, all without using the Bible as a starting point. But the most common explanation is that it originated with the ancient Babylonians (around sixth century BC).

One popular example is from a paper written by an instructor at Colorado State University that reads, “we can thank the Babylonians for our seven-day week.”1 The paper essentially states that the Babylonians get the credit for “inventing” the seven-day week model, based on the number of visible celestial bodies they could observe at the time, which happened to be seven (Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn). This number apparently held (mystical) significance to them.2

This author goes on to say, since the Babylonians were such a dominant culture in the Near East, this seven-day model was eventually adopted by other prominent civilizations like the Jews (captives in Babylon at that time), the Persians, and the Greeks. Finally, the Romans picked it up, and it was formally adopted by Emperor Constantine in AD 321, thus becoming the official week across the known world.

At first glance, that all sounds reasonable, but if we stop to examine that claim from a biblical worldview, we quickly realize that explanation is actually backward.

At first glance, that all sounds reasonable, but if we stop to examine that claim from a biblical worldview, we quickly realize that explanation is actually backward. There is evidence of a seven-day week in Noah’s day, as that is the most logical reason that Noah waited seven days between sending out the birds as the floodwaters were receding (Genesis 8:6–12). As cultures dispersed at the Tower of Babel, they took the seven-day week with them.

No doubt there would be times when people would try to deviate from this seven-day format, but they kept coming back to a seven-day week. Most likely the Babylonians, who are descendants of Noah’s son Shem and great-great-grandson Eber (consider Genesis 11:14–17; Jeremiah 51:24; Ezekiel 23:15; Nehemiah 9:7), inherited this seven-day week like everyone else. If they had deviated, then it is possible that they re-adopted the seven-day week model from the Jewish (and other) people who were exiles in Babylon (2 Kings 25).

What Does the Bible Say About the Origin of the Week?

Clearly, the attempts by secular historians to explain the seven-day week don’t even consider the actual (obvious) explanation (Romans 1:18–23), which is that our seven-day week was established from the very beginning by our almighty God, as we plainly read in Genesis 1–2.

Thus the heavens and the earth were finished, and all the host of them. And on the seventh day God finished his work that he had done, and he rested on the seventh day from all his work that he had done. So God blessed the seventh day and made it holy, because on it God rested from all his work that he had done in creation. (Genesis 2:1–3)

God’s Word makes it clear that he created everything in six literal days (as plainly defined per the Hebrew word for day, “yom”) and rested on the seventh day. By the way, creating the universe in six days is not a problem for an all-powerful God since nothing is too hard for him (Jeremiah 32:17).

Note, this is not saying God rested because he was tired or fatigued (Psalm 121:3–4), nor does it imply (as some people argue) that the seventh day is an “eternal day,” but rather God “rested” when he ceased his creative work on the seventh day as a basis for our workweek.

But you might be wondering, why did God take six days to create everything, since he (easily) could have created everything in an instant, right? Well, the short answer is . . . because he’s God and he does as he pleases (Psalm 115:3). But aside from that, God decided to create in six days and rest on the seventh day as a pattern for us to follow, thus dedicating to all of us six days for working and one day for resting (Exodus 34:21). Based on the creation week, God further defends this work and rest weekly cycle of 7 days in Exodus 20:11 and 31:17. That’s why we see companies and organizations today still using this weekly cycle to cease their business on Saturday and/or Sunday.

What Else Does the Bible Say?

Moreover, we consistently see the significance (and the symbolism) of the seven-week model throughout the Bible. Particularly, when God orchestrated the global flood events during the account of Noah, He did it in terms of seven-day week cycles, as seen in Genesis 7–8.

For in seven days I will send rain on the earth forty days and forty nights, and every living thing that I have made I will blot out from the face of the ground . . . And after seven days the waters of the flood came upon the earth. (Genesis 7:4, 10)

He waited another seven days, and again he sent forth the dove out of the ark. And the dove came back to him in the evening, and behold, in her mouth was a freshly plucked olive leaf. So Noah knew that the waters had subsided from the earth. Then he waited another seven days and sent forth the dove, and she did not return to him anymore. (Genesis 8:10–12)

And by adding up each of the times recorded, we see that Noah and his family exited the Ark 371 days (53 weeks) after first entering it! God truly is amazing in his sovereignty.

Furthermore, the seven-day week is repeatedly affirmed by Moses in the book of Exodus.3 For instance, in the establishment of the Passover in Exodus 13, in the experience with the manna in the wilderness in Exodus 16, and with the giving of the Sabbath (i.e., “Shabbat” in Hebrew, simply meaning “rest”) Commandment as part of the Decalogue in Exodus 20.

Seven days you shall eat unleavened bread, and on the seventh day there shall be a feast to the Lord. Unleavened bread shall be eaten for seven days; no leavened bread shall be seen with you, and no leaven shall be seen with you in all your territory. (Exodus 13:6–7)

Moses said, “Eat it today, for today is a Sabbath to the Lord; today you will not find it in the field. Six days you shall gather it, but on the seventh day, which is a Sabbath, there will be none.” On the seventh day some of the people went out to gather, but they found none. (Exodus 16:25–27)

For in six days the Lord made heaven and earth, the sea, and all that is in them, and rested on the seventh day. Therefore the Lord blessed the Sabbath day and made it holy. (Exodus 20:11)

Sadly, over time the Israelites neglected the original purpose of the seven-day week model (that is, to observe the Sabbath for their benefit) and distorted it into a mere religious “ritual,” mainly by the Pharisees (leaders in the Jewish synagogues). God himself later rebuked them when he became flesh (John 1:1–14) in the person of Jesus Christ. During Jesus’ earthly ministry, being the Lord of the Sabbath (Matthew 12:8), he admonished the Jewish leaders stating that “the Sabbath was made for man, not man for the Sabbath” (Mark 2:27), thus reminding them of its true purpose.

But these words weren’t just for the Pharisees; we all need continual reminders that it’s for our own good, both physically and spiritually, to have a day of rest.

But these words weren’t just for the Pharisees; we all need continual reminders that it’s for our own good, both physically and spiritually, to have a day of rest. And ultimately, this should regularly remind us of the One who created and sustains everything by the Word of his power (Hebrews 1:1–3).

Then over time, as the gospel was preached to every nation (e.g., Matthew 28:18–20; Romans 1:8), Christians all over the world began observing one day out of the week to honor the Lord, which usually varied between the seventh day (Saturday) and the first day (Sunday) of the week. Traditionally, in celebration of Christ’s resurrection, the early church would preach to the Jews in the synagogues and the Temple on Saturdays (e.g., Acts 13:14, 13:44, 18:4) and used Sunday (i.e., the Lord’s Day) as their day for corporate worship. For instance, in the New Testament, we read,

On the first day of the week, when we [the disciples] were gathered together to break bread, Paul talked with them, intending to depart on the next day, and he prolonged his speech until midnight. (Acts 20:7)

On the first day of every week, each of you is to put something aside and store it up, as he may prosper, so that there will be no collecting when I come. (1 Corinthians 16:2)

However, since there is no explicit command for either Saturday or Sunday in the New Covenant in Christ’s blood, Christians have always had the freedom to observe either day of their choosing per 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. The one who eats, eats in honor of the Lord, since he gives thanks to God, while the one who abstains, abstains in honor of the Lord and gives thanks to God.

Due to this combination of Saturday/Sabbath and the Lord’s Day, many nations ultimately have a two-day “weekend” of rest and recuperation. It is interesting how many non-Christians are blessed by a weekend, unbeknownst to them that they are technically Christian holidays.

The Seven-Day Week Was Created for Us

Practically speaking, this is why every human is really “pre-wired” (predisposed) to a seven-day week. And it explains why even atheists (those who reject God and His Word) still decide to “rest” on the weekends. This ultimately shows that they are actually borrowing from the biblical worldview since, from a naturalistic worldview, it really makes no sense to adhere to such a pattern. In other words, atheists should thank God for their weekend!

Practically speaking, this is why every human is really “pre-wired” (predisposed) to a seven-day week. And it explains why even atheists (those who reject God and his Word) still decide to “rest” on the weekends.

A good example to show this predisposition toward the seven-week pattern is when the French in 1793 tried changing their week to ten days long (as part of the “French Revolutionary Calendar”) and, as expected, it didn’t work out at all. In summary, there were many problems,4 but the main issue was that ordinary French workers were being required to work nine days before getting just one day off. This inevitably led to many becoming not only severely overworked but also very depressed. (Just remember this the next time you complain that the workweek is too long!)

Conclusion

So by starting from God’s Word, we clearly see that the seven-day week was created for our physical and spiritual benefit of having a dedicated day of rest and worship (although, as Christians, we should be worshipping the Lord every day of the week).

But more importantly, as the writer of Hebrews puts it (Hebrews 4:1–11), the ultimate “rest” for God’s people is provided only through Jesus Christ, who is our eternal Sabbath rest. The One who offered for all time a single sacrifice for sin and sat down at the right hand of God because his work was finished (John 19:30) is reigning today from his throne, making all his enemies a footstool for his feet (Hebrews 10:12–13).

To learn more on how you can find a genuine rest from your works and be reconciled to God, check out the bad news and the good news.