The origin of Genesis chapter 1
I have the greatest respect for Christians and I certainly don't like upsetting Christians but I am after all an atheist so sometimes I feel that I should treat the Bible in a purely scholarly way rather than as a source of religious truth. It is an immensely important document so deserves all the scholarly examination it can get. And Genesis chapter 1 is one area where scholars find something very different from what Christians believe. So I recommend at this point that Christians read no further what I have to say here.
The need for Genesis chapter 1 arose from the fact that the ancient Israelites always used the Babylonian calendar, which divided the week into 7 days. That calendar was so widespread from about 4,000 years ago that it would have been disruptive to use anything else.
So how did the Babylonian calendar arise? It arose because the Babylonians were pretty keen astronomers, who closely observed the night sky. And the big discovery they made was that most of the stars were fixed relative to one-another but five of them were not. There were five "wandering" stars that kept moving around. We know them as Jupiter, Saturn, Mars, Mercury and Venus.
We know that they are planets but the Babylonians had no inkling of that. It seemed to them that entities that moved among the stars must be gods and you had better respect them accordingly. But there were also two other bodies that moved about the sky: The sun and the moon.
So some very holy Babylonian had the bright idea that each of these seven gods should be regularly worshipped in a seven day cycle, so that you kept all the Gods onside. This was seen as a brilliant proposal in the ancient world and so we came to have a 7 day week. Each god got a bit of respect every 7 days. And the sun was obviously the big chief so his day was especially holy. And it still is. Most people still go to church on Sunday.
But the Israelites were a rather rebellious and cantankerous people (as their own prophets often said) so they refused to have their main religious observations on Sunday. They chose Saturday instead -- to differentiate themselves from all the sun-worshippers around them. The pagans made Sun-day the first day of the week so the Israelites worshipped on the 7th day of the week. That was also Saturn's day but too bad about that. And Jews still worship on Saturday
But the Jews never did. But that left them with a problem. They vigorously rejected Sun worship so how come they used the 7 day pagan calendar that the sun worshippers did? They had to find some way of explaining their use of the 7 day calendar that did not go back to the Babylonian gods.
And Genesis chapter one was the answer. There was already a perfectly good creation story in Genesis. In our Bibles it starts from Genesis 2:4. And we know it is the original start of the Bible because it uses the divine name YHVH ("Yod He Vau He" in Hebrew) all the time, as does the rest of the Old Testament. Hebrew originally had no vowels so the original pronunciation of YHVH is a matter of debate but "Yahveh" with the "H" pronounced as in the German "Ach Laut" or the "ch" in the Scottish "loch") is most probable. Englishmen can't say that, however. Modern English has lost all its gutturals. So in English we say "Jehovah".
But tacked on in front of the original brief creation story we now have a much more elaborate creation story that tells us that the creation unfolded in 7 "days" or time periods. Voila! We now have a Jewish explanation for the use of a 7 day calendar! It was the creator himself who divided the days into a 7 day cycle. It was now nothing to do with Babylonian sun worship. Problem solved. The Babylonian explanation for a 7 days calendar had never been challenged before, though. Everybody thought it was obvious. But now there was an exception. The pesky Jews had another story.
So how do we know that Genesis chapter 1 was written as a late bit of Israelite propaganda? Easy. Genesis chapter 1 does NOT use the divine name. One would expect the creation story to be full of the name of the Hebrew god but it is in fact not to be found there. Instead of YHVH we find "elohim", which is just the name for gods generally. It is however the plural form of "god" so could naively be translated as "gods" (the singular is "Eloah", which is where Arabs get "Allah from). But it is common to use plurals as respectful forms of a word or name. The Queen of England, for instance, always refers to herself on formal occasions as "we". So the chapter 1 authors substituted a respectful form of "god" instead of the divine name.
So why is that significant? Because avoidance of the divine name is a bit of Jewish pietism that arose some time around the 3rd century B.C. In order not to use the divine name in vain, Pharisees and their like thought it safest not to use the name at all. So they didn't. And that usage was well ingrained by the time of Christ. So the New Testament does not mention YHVH. It uses "ho theos" (the god) instead, which is how the ancient Greeks referred to the local god being worshipped.
So chapter 1 clearly was written after use of YHVH became impious. It is later than the rest of the Bible, which routinely uses YHVH. And to this day, most Bible translations do not use YHVH where it occurs. The King James Bible uses "the LORD" (in all caps) where YHVH occurs in the original.
So if they were textual scholars, Christians could well argue that Genesis 1 is not really a part of the Bible. It is just a bit of Jewish propaganda. Since the creation story of Genesis 1 is often an embarrassment, that could be useful.
It is probable that the 7 day creation story was not entirely original when it was tacked on to the front of the Bible long after the rest of the Bible had been written. Tacking something new on like that would have been resisted by the priestly guardians of the text. That there was careful guardianship of the text is suggested by the similarity of the text of Isaiah found in the Dead Sea scrolls and the more modern Masoretic text (from about 800 AD).
So the 7 day creation story was likely a respected legend or oral tradition long before it was elaborated and written down for what we now know as Genesis chapter 1.
In support of that view is that we find the 7 day creation story stressed in the Exodus 20 version of the ten Commandments. Exodus is undoubtedly canonical and uses YHVH quite a lot. But could the mention in Exodus be an interpolation? Could it too have been added in later?
Alas! That is all too probable. The version of the 10 Commandments in Deuteronomy 5 does NOT contain mention of a 7 day creation. It commands a 7th day Sabbath only. That is also true of the "expanded" version of the Commandments in Exodus 34 (See verse 21).
So there is no doubt that the 7 day creation story was added on long after the rest of the Old Testament was written.