The Weekly Cycle points to the Sabbath.

I came across a discussion on whether understanding the Creation account as literal or non-literal, affects our understanding of Gods truth. When you read the Bible or any book for that matter, you must look to see if the author intend it to be fiction or actual events. One must first demonstrate from the given text that the author did not intend for anyone to read his words as a literal historical account. Any assertion that states that a non-literal reading is the most appropriate reading must provide evidence of specific figurative indicators in the text such as metaphors, similes allegories, hyperbole, symbolism and such.

Well it is very clear the weekly cylcle was set up and Sabbath was given to us at creation as the seventh day of the week as we read in Genesis. The various days of the week were in ancient times called the first day, the second day, etc., for these were their Biblical names. But Satan wanted to see if he could throw off the idea of a weekly cycle or the numbering so as to veil the seventh day, and by Roman times, non-Christians began calling them the day of the sun, the day of the moon, etc., in honor of different heavenly bodies. This was known as the "planetary week."

The Babylonians tracked the Sun, Moon, and the five planetary bodies they knew of and believed that each of these seven celestial bodies was ruled by a god or goddess. In the seven-day week of the Babylonian calendar, each day was influenced by a particular god or goddess.

Greeks from the Hellenistic period pick up the seven-day “planetary” week, naming the days after their own deities with Helios, Selene, Ares, Hermes, Zeus, Aphrodite, and Cronos. The ancient Romans adopted the seven-day week, basing the day names on the known planets, Sun, and Moon and their own deities.

Each day was ruled over by a different pagan god, but the most important of all gods was given the rule of the first day of the week, with the idea in mind that the first is always more important than that which follows it. The most important of all gods was given the rule over the first of the seven days. It was his day, the day of the Sun, and all the worship of the week centered on his day.

Now, although these names for the days of the week were new, the sun god wasn't, for his worship came from a devotion to that most powerful of natural objects. It was one of the most ancient forms of worship and is represented by solar disc images found on nearly every continent of our world. So Satan used a form that was known all throughout the earth, the heavens and its bodies, very sly.

By changing the names he could veil the seventh day in the cycle and at the same time bring in the worship of the sun. This was idolatry of the highest degree as it could be passed on no matter the people, language or nation, and it was.

"Sun worship was the earliest idolatry."--Fausset, Bible Dictionary, page 666.

The Arabians appear to have worshiped it directly without using any statue or symbol (Job 31:26-27). Abraham was called out of all this when he went to the promised land. Ra was the Sun god in Egypt, and On (Heliopolis) was the city of Sun worship (see the Hebrew of Jer. 43:13). But the Jewish week was always divided into seven days, but instead of being based on the planets tied to pagan deitis, this system was tied to the account of Creation in the Hebrew Bible and the days had numbers with the seventh day being the Sabbath. However, entering Canaan under Joshua, the Hebrews again met Sun worship, that of Baal, which God clearly condemned.

So Satan has been trying with every means in his disposal to draw Gods people away from the true worship, from the Sabbath, the seventh day of the week. And if he can break the weekly cycle or change the days so as to make them indistinguishable, he could accomplish his purpose, yet the weekly cycle remains, and testifies to Gods seventh day Sabbath.

Here is a interesting article I came across...

"By surprise, science has discovered amazing seven-day cycles in the very building blocks of plant and animal life. These newly found sevens, or "septans," also lie buried in us humans -- deep in our metabolic, hormonal, and neuronal networks. This startling discovery has wide-ranging effects that you will want to understand. The following article explores those effects by answering three questions. First, does the formerly unknown, automatic rhythm of sevens hold the secret to one of history's most perplexing enigmas -- the origin of the seven day week? Second, what could these innate, autonomous rhythms mean for us? And lastly, what will this new knowledge tell us about the biblical Sabbath and the Creator God?

Society's seven-day calendar week is the only major rhythm of human activity that is totally oblivious to external nature. This so-called "social week" rests on mathematical regularity alone. We may casually assume that our week is really a division of the moon cycle. If that is our assumption, we forget that the lunar cycle is not a twenty-eight-day cycle, but approximately twenty-nine days, twelve hours, forty-four minutes and three seconds -- or 29.5306 days between new moons. A precise quarter of the lunar cycle amounts to the uneven figure of 7.38625 days. So any week using that true length would begin at different times of the day every time the cycle started. There is just no way to neatly divide the lunar cycle into weekly blocks of complete days.

Then what about the sun? Doesn't the cycle of seven relate to the center of our solar system? Again, no! The 7-day week is also independent from the annual solar cycle of 365 1/4 days. A "year" of 52 weeks would have just 364 whole days. Nor is the week in harmonic sympathy with the star year of 366 1/4 days. Star days or "sidereal days" are about four minutes shorter than solar days (an observer will see a particular star at the same position four minutes earlier on successive nights). In short, there are no known external rhythms in nature that could explain the near universal existence of the seven day social week.

Yet, the importance of the seven-day week -- or heptad, a series of seven -- is monumental....Apart from the biblical record, historians have had difficulty placing the precise beginning of the seven-day week. It is simply acknowledged as an ancient practice of very early origin in the evolution of civilization."...The Amazing 7-Day Cycle (Part 1)