Moses was the author of the Pentateuch, which is name given to the first five books of the bible (Genesis, Exodus, Leviticus, Numbers and Deuteronomy). All the books, except for Genesis, relate to the time Israel spent in the desert after leaving Egypt. Genesis is important in this context because Moses was not alive when the events the book describes occurred.
The book of Genesis is one of the most important books in the bible. It consists of the history of creation, the fall of mankind, the first civilization, and the flood and it ends with a history of the origins of the Hebrew race, i.e. that of Abraham (who was an elect) and his family.
To understand how Moses wrote Genesis, we must go forward to the events described in the book of Exodus.
Moses chosen by God
Moses fled Egypt in Exodus 2 after murdering an Egyptian man. He went to the land of Midian (which was probabaly somewhere near the Sinai Peninsula) and lived there, marrying the daughter of Reuel (Jethro).
In Exodus chapter 3, Moses was looking after the flock of Jethro at Mount Horeb “the mountain of God” (verse 1). Mt Horeb is the same place as Mt Sinai (we know this because later on God comes upon Mt Sinai to meet the Israelites after telling Moses to bring them to the same mountain where he appeared to Moses in the burning tree). Moses saw the angel of the Lord in a tree that was on fire yet was not burnt (verse 2). God called Moses’ name and told him to take his shoes off and not come near because Moses was standing on holy ground (verses 4-5).
God then tells Moses to go to Egypt and bring the Hebrew people out of it to worship Him on “this Mountain” i.e. Mount Horeb/Sinai (verse 12). God reveals his name to Moses as “I AM WHAT I AM” and as “I AM” (verse 14).
God’s glory on Mt Sinai
In chapter 19, after Moses completed his task of bringing the Hebrew people out of Egypt, he led them to the desert and into the Sinai Peninsula. They set up camp at the base of Mt Sinai (verse 2) and God told Moses that He would come down upon the mountain in the view of everyone (verse 11). On the third day, there was thunder and fire and a thick cloud on the mountain and the sound of a horn being blown; this was so loud that everyone became afraid. God then told Moses to come up the Mountain which he did (verses 16-20).
God gave Moses the 10 commandments and some of the law, which Moses went back to the people to tell them about in chapters 20-23. In chapter 24, Moses carried out some ceremonies with the people which God told him to do. He then went back onto the mountain and the glory of the Lord was on it. The glory looking like devouring fire to the people (God is called a consuming fire in Deuteronomy 4:24 and 9:3, as well as in Isaiah 30:27-30 and Hebrews 12:29).
Moses stayed in the mountain for 40 days and 40 nights. When Moses was on the mountain, God wrote the 10 commandments (verse 12). In chapters 25-31 God gives Moses instructions on making the tabernacle and the Ark of the Covenant in addition to instructions about the new priesthood.
The people sin
In chapter 32, the Israelites forced Aaron (Moses’ brother) to create an idol for them to worship and God knew about this and told Moses (verses 1-7). God would have destroyed them but Moses intervened and pleaded with God not to do so.
Side note: in verse 14 it says that God “repented of the evil which he thought to do unto his people”. This doesn’t mean God considered His actions, thought they were wrong, and wished He didn’t do them. Modern usage of “repentance” makes the term misleading when accredited to God. It may be more accurate to say that God “relented.” God is all knowing so He doesn’t get new information, nor does He make errors. In this context, “repenting” means for God to take a different course of action to what He would have taken if the people continued with their sin. We can see this pattern elsewhere in the bible. Jonah’s sermon to Nineveh was “Yet forty days and Nineveh will be overthrown” (Jonah 3:4). If we take this statement on a purely factual basis, it is untrue, since when Nineveh repented, God also relented of the disaster He had planned. God’s word to Nineveh had an unstated contingency, just as God’s word against Israel had an unstated contingency.
When Moses went down to meet the people he saw them partying and got so angry he threw down the tablets of stone with the 10 commandments written on them (by God Himself, see verses 15-16) and they broke (verse 19). After Moses had carried out judgement upon the wrongdoers, he went to God to ask for forgiveness for the Israelites, even going as far as to ask God to blot his name from the book of which God has written if God doesn’t forgive their sin. I believe the book Moses is referring to is the Jesus’ book of life mentioned in Revelation 3:5). Moses’ intercession for the people of Israel just goes to show how great a leader he is. God responds that He will punish those who are responsible for their own sin directly (verse 33).
After this ordeal, in chapter 33, Moses entered the tabernacle and the pillar of cloud descended and stood at the door of the tabernacle, and God spoke with Moses directly (verse 9).
Moses begged God to show him God’s glory but God responded that no man can see His face and live (verses 18-20). God then told Moses that He would pass Moses by and put him in a hole in a rock and cover Moses with His hand when He goes past and then remove His hand so that Moses can see His back (verse 33).
Moses sees God’s back
In chapter 34, the next morning, Moses goes into Mt Sinai as instructed, with 2 new tablets of stone and in verses 6-7 God passed by Moses and proclaimed His name “The Lord, The Lord God, merciful and gracious, long-suffering, and abundant in goodness and truth, keeping mercy for thousands, forgiving iniquity and transgression and sin, and that will by no means clear the guilty; visiting the iniquity of the fathers upon the children, and upon the children’s children, unto the third and to the fourth generation”. Moses then bowed then and worshipped God (verse 8).
So Moses saw God’s back and I believe that when he did this he saw the past all the way back to creation, the Garden of Eden and everything that happened in Genesis and the beginning of Exodus. This was how he was able to write Genesis. It is recorded that he spent 40 days and 40 nights on the mountain with God (verse 28), without food or water, because God must have sustained him. I strongly believe that he wrote Genesis during this period. Also, it may be that the reason no man may see God’s face is that they would see the future when looking upon His face.
When Moses eventually came down from Mt Sinai, his face was shining brightly and he didn’t realise it. Aaron and the rulers of the people saw his face shining brightly and were scared to come near him. Moses had to resort to putting a veil over his face to cover it.
What we can glean from this is that the more time we spend with God, the more we become like him and his light can pass on to us. Moses’ encounters with God starting with the burning tree and culminating with seeing God’s back on Mount Sinai changed his life. Moses was one of the greatest leaders and prophets that Israel had. Centuries after he died, he had the privilege of appearing with the transfigured Jesus on a mountain in Matthew 17:1-6. This was another time he saw God’s glory while on a mountain. We should pray that as we spend more time in God’s presence, his light should shine on us so that we may become more like Him.