The original question was: Why do people say Moses is the author of Genesis when the book doesn’t even mention his name?
Answer by John Mackay
There is more evidence concerning Moses’s authorship of Genesis that we can consider! The Hebrew Scriptures have always included an introduction to Psalm 90 advising us that Moses is the author. The contents of this Psalm are most revealing as the one thing you can conclude from Psalm 90 is that Moses had access to and direct knowledge of the contents of Genesis through Deuteronomy in the order we still have them.
The Psalm begins with Creation and the Creator v1 and 2, (cross reference Genesis chapters 1 and 2). Then sin and judgement (Genesis chapter 3) are referred to when we are reminded that God’s judgement is death and returning to dust (v3). Next the Psalm moves on to mention times spans of 1,000 years (v4), which less than coincidentally is similar to the vast life spans of people in Genesis chapters 1 to 6, of up to 969 years.
It then hinges around the term ‘flood’ (v5) and passes onto mankind’s shorter lifespan post Noah’s flood, and post Exodus, where unless the Lord strengthens your body or lengthens your days, you last a maximum of 70 – 80 years (v10). That by the way was the upper age limit that could be expected for the rebellious adults who had left Egypt and had been judged by God to wander 40 years until they died. Moses is a good example of the exception, in living to age 120 with a still strong body and good eyes (Deuteronomy 34:7). At which point God took his life on Mount Nebo (Deuteronomy 34: 5-6), just before the Israelites entered the Promised Land.
Note that all the literary clues in the Psalm tell us it was written after the Israelites left Egypt (Exodus chapter 14) and before Moses died at 120 years old (Deuteronomy chapter 34). Coincidentally the last time we saw a reference to man’s days being 120 years was in Genesis 6:3, spoken to Noah, pre-flood.
All of which forms a good background for Moses to make the key point that whether our life span was 1,000 years pre flood, or as low as 70 or 80 years post Exodus, or even his own extraordinary 120 years, compared to the Eternal Creator our days are so few. Therefore every one of us needs to be careful with what we do with the time the Lord God gives us. And all of this only adds to the case that Moses was not only the recorded author of Psalm 90, but also the author of Genesis.
In addition, this Psalm has great use in defeating people who want to make the days of creation vast ages. See the questions:
DAYS: The New Testament says “a day is as a thousand years” to God. Why can’t Genesis days be long times? Answer here.
DAYS: Peter says a day is like a thousand years. How can you insist Genesis days are 24 hours? Answer here.
A PDF article of all three parts can be downloaded here.
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