If the foundations be destroyed, what can the righteous do? (Psalm 11:3 KJV)
Calling the book of Genesis foundational is indeed a huge understatement. It is a book that soundly refutes the religions of atheism, pantheism, polytheism, humanism and evolution. It is written in clear historic prose and should be read with that understanding in mind. Of course, the Bible student will always do well to look for key phrases that indicate it should be considered otherwise. It is clearly accepted as historic prose by the apostles Peter and Paul as well as by Jesus himself, who referred to Genesis more than any other Old Testament book. When its scientific facts are presented in model form and laid down next to the current uniformitarian model, it better represents the evidence. So, as we proceed to build on the foundation that has already been laid, we can have confidence that this foundation is strong. Let's also recognize that indeed, it is a 'solid rock' on which the church should take its stand.
Therefore whosoever heareth these sayings of mine, and doeth them, I will liken him unto a wise man, which built his house upon a rock: (Matthew 7:24 KJV) Jesus speaking.
Since Genesis means Beginning, let's look at some of the many firsts which occur in this book that help to make it the foundational marvel that it is:
It begins with the four words "in the beginning God". We learn through further study that the Hebrew word used for God is Elohim which is the plural form for God. This is our first clue of the Triune nature of God. Further clues are seen in the work of the Spirit in verse 2, and the plural language in verse 26a". And God said, Let us make man in our image, after our likeness:" (emphasis mine). We further learn that this creation by God is done Ex Nihilo (latin), meaning out of nothing. Using the Bible genealogies, we know that this occurred approximately six thousand years ago.
We learn here that mankind began as vegetarians before the fall, verse 29, chapter 1. This is appropriate as death only came after the fall with the introduction of sin.
An early mention to Adam and Eve of a future redeemer is first mentioned in Genesis 3:15. This is later fulfilled in the death, burial and resurrection of Jesus in roughly four thousand years from this time.
We learn that the unchecked manner of fallen man leads to a world "filled with violence" (Genesis 6:13). So, we are introduced to Noah and his family, whom God will use to build an Ark to allow the human race and other life on earth to continue. He then destroys the rest of the world in a global flood.
After the flood, with the building of the tower of Babel in chapter 11, we then see God disburse the rebellion with the introduction of many languages.
We receive a clear understanding of the nature and manner of marriage. (Genesis 2:24)
We are introduced for the first time to the idea of one man for one woman for one lifetime. Our fallen world, with an exception later mentioned by Jesus (Matthew 19:9), has left our modern understanding of marriage to be "found wanting".
We are told in the creation account, that God created everything "after their kind". We would also later understand that God designed great genetic diversity into His creation, which allows for adaptation of his creation to a more hostile world.
Our introduction to the use of clothing begins in Genesis 3:7 and later by God in verse 21 of the same chapter.
We are introduced to the first murder in chapter 4 when Cain murdered his brother Abel.
Immediately after the flood, we are introduced to government for the first time. Human government will have the authorization from God to exercise the death penalty. (Genesis 9:5,6) This again seems very appropriate based on the widespread "violence" that led to the destruction of the whole world.
We see the introduction of eating meat after the flood. (Genesis 9:3)
This list above is not exhaustive. But, it does help us to see many of the "firsts" that are found in the early chapters of Genesis. It also helps us to see the bedrock upon which many of our current customs/laws are built. Beginning with Seth and continuing through the life of Abraham, his son Isaac and his son Jacob, we see the messianic line as it leads us directly to Jesus. Truly, this book is foundational! God's people would do well to study it, and see God's hand at so many points in history (His Story).