I will give you that it is remotely possible, but highly improbable. I am granting a slight margin of possibility because nowhere does the Bible state unequivocally that Moses is the author of Genesis. HOWEVER, there are multiple references, OT and NT, which state that he in fact did author the exodus story and the rest of the law.
Now to why I consider it highly improbable. You know this but bear with me. The Jews separate their Tanakh into 3 groupings - the Law, the Prophets and the Writings (the Psalms). The Law, or Torah, encompasses the first five books, including of course Genesis. Jesus refers to Moses and the Law interchangably, and He Himself refers to the Law of Moses, the Prophets and the Psalms as 3 separate groupings. Good example of attributing the authorship of Moses to the Law -
Luke 24:44 And he said unto them, These are the words which I spake unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses, and in the prophets, and in the psalms, concerning me.
The most obvious response to that is that Jesus somehow meant only the law specifically as found in Exodus, Leviticus, Deuteronomy etc. The problem with that is that there is no other author ever mentioned by anyone with regard to the other parts of the Torah. And the authorship of the rest of the OT is reasonably self-evident. I believe that if there were another author, his name would have been noted in some regard, if for no other reason than the sheer importance of the book of Genesis - there is so much packed into it - the creation, the fall, God's relationship with man, the flood, His covenant with Abraham, the sacrificial model of Isaac, the families of Jacob, the life of Joseph which led the Israelites into Egypt. But rather, we have only Moses as the first author.
In your last post to me you wrote
I don't believe it's the same writer. I (and many others) can hear two distinct voices. Not just in Genesis, but through out the Pentatuch. But your scenario makes sense as well, if you don't believe in the theory of mutliple writers.
If Jesus Himself attributed the Pentateuch to Moses, how can you get around his authorship?
Mark 12:26 And as touching the dead, that they rise: have ye not read in the book of Moses, how in the bush God spake unto him, saying, I am the God of Abraham, and the God of Isaac, and the God of Jacob?
Luke 24:44 And he said unto them, These are the words which I spake unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses, and in the prophets, and in the psalms, concerning me.
Some other examples -
Exodus 17:14 And the LORD said unto Moses, Write this for a memorial in a book, and rehearse it in the ears of Joshua: for I will utterly put out the remembrance of Amalek from under heaven.
Deuteronomy 31:24 And it came to pass, when Moses had made an end of writing the words of this law in a book, until they were finished.
Joshua 1:8 This book of the law shall not depart out of thy mouth; but thou shalt meditate therein day and night, that thou mayest observe to do according to all that is written therein: for then thou shalt make thy way prosperous, and then thou shalt have good success.
Joshua 8:34 And afterward he read all the words of the law, the blessings and cursings, according to all that is written in the book of the law.
35 There was not a word of all that Moses commanded, which Joshua read not before all the congregation of Israel, with the women, and the little ones, and the strangers that were conversant among them.
Malachi 4:4 Remember ye the law of Moses my servant, which I commanded unto him in Horeb for all Israel, with the statutes and judgments.
John 1:45 Philip findeth Nathanael, and saith unto him, We have found him, of whom Moses in the law, and the prophets, did write, Jesus of Nazareth, the son of Joseph.
John 1:17 For the law was given by Moses, but grace and truth came by Jesus Christ.
Acts 28:23 And when they had appointed him a day, there came many to him into his lodging; to whom he expounded and testified the kingdom of God, persuading them concerning Jesus, both out of the law of Moses, and out of the prophets, from morning till evening.
In your original post in the other thread you wrote
Well, duh! Who doesn't know that the Bible is a LIBRARY of books? Who doesn't know that the books of the Bible were written at different times, by different people and for different audiences? Who doesn't know that this collection of books has been highly edited at different times, by different people and for different audiences?
I still disagree with you, feeling that you haven't shown any credible evidence so far. It seems to me that the biblical text itself testifies to the opposite. Do a study on scripture quoted by Jesus - note to whom He attributes His quotes. For example, there has been a theory out there for some years that there were actually two authors of Isaiah - one for the first 39 chapters and one for the last 27 chapters - because the style and messages are radically different. But in the gospels, Jesus attributes parts of the first half as well as parts of the second half to Isaiah, so is Jesus wrong about the authorship?
Another interesting note is that the text of Isaiah seems to parallel the entire 66 books of the Bible, with the first 39 chapters speaking of condemnation and the last 27 of redemption. I find it peculiar that there are 39 books in the OT and 27 in the NT, but that is an entirely different thread. :)
Anyway, the claim of "highly edited" is a pretty drastic one. My opinion is that if one believes the salvation message of Jesus, enough to call Him Saviour, one is obligated to take the rest of His words as documented in the gospels as valid as well. And from what I can gather, Jesus Himself in no way supports the idea that the Pentateuch had multiple authors or that the Tanakh was highly edited in any way. How could He expect people to believe what He claimed the OT said about Him if there was any chance that the very prophecies were suspect as a result of editing over the years? The disciples would have been a bit more sceptical, don't you think, if they couldn't be completely sure that the words they held in their hands were the same as those originally given to the prophets. If the OT has been changed, then the entire message and ministry of Jesus is questionable, for the prophecies He fulfilled were detailed and specific.