Genesis 7:21-24 meaning

It was no less than utter destruction of the earth. It must be noted that fish did not die in the flood. All flesh that moved on the earth perished (v 21). This would not include all life in the water. The subsequent list emphasizes this point: birds and cattle and beasts and every swarming thing that swarms upon the earth, and all mankind died in the flood (v 21). The life in the water was spared, only of all that was on the dry land, all in whose nostrils was the breath of the spirit of life, died (v 22).

The whole human race, except Noah and his family, were destroyed. The New Testament validates the worldwide destruction of the flood. The Apostle Peter wrote, under the inspiration of the Holy Spirit,

"through which the world at that time was destroyed, being flooded with water"
(2 Peter 3:6).

The flood destroyed the entire world at that time. When Noah disembarked, he entered a new earth. It is likely he encountered a new climate, new continents, and new geography. 

The flood water was on the earth one hundred and fifty days (v 24), or five months, before the waters began to recede. Noah and his family became the remnant that survived and escaped the judgment due to Noah's faith. Only Noah was left, together with those that were with him in the ark (v 23). They were saved physically in order to replenish the earth once again.

In the Flood account, the message is unmistakable, God's judgment and mercy. However, by looking carefully at the details, we find that there is more that can be learned. To gain a more complete understanding of what the Bible says, one should not only look at the content but also its arrangement. How it is arranged is referred to as its "literary structure." The Bible uses a variety of different literary techniques to communicate its message (i.e., allusion, hyperbole, metaphor, simile, etc.). It helps to know and recognize when these techniques are being applied in scripture.

One type of literary structure found in scripture is called a chiasm or chiastic structure. A chiasm is a literary device in which a sequence of ideas is presented and then repeated in reverse order. The structure of a chiasm is usually represented by a series of letters, each letter indicates a new thought or concept. For example, the structure ABBA refers to two ideas (A and B) repeated in reverse order. Often, a chiasm includes another idea in the middle of the repetition: ABXBA. In this structure, the two concepts (A and B) are repeated in reverse order, but a third idea (X) is inserted before the repetition. In this structure, the central idea is being emphasized by the surrounding structures.

Biblical writers used chiasms to add emphasis to their writings and to highlight details of particular importance. One example is found in Genesis 9:6, "Whoever sheds man's blood, by man his blood shall be shed." The first section is repeated in reverse order by the second section.

Paying close attention to the literary structure of the Flood account reveals many truths. In Genesis chapter 7 and 8, we find two chiasms that are important, one of key numbers and one of the key events.

Interestingly, the organization of key numbers marking the progression of time in the Flood account has a chiastic structure. The chiasm opens with "seven days" (7:4, 7:10) and closes with "seven days" (8:10, 8:12). Next, we see a reference to "forty days" (7:12), which appears later, in reverse order ("forty days," 8:6). At the center are two references to "one hundred fifty days" (7:24, 8:3), which bracket the key verse and central theme of the flood narrative, "God remembered Noah" (8:1).

A. "Seven days" (7:4, 7:10)

B. "Forty days" (7:12)

C. "One hundred fifty days" (7:24)

D. God's Remembrance of Noah (8:1a)

C'. "One hundred fifty days" (8:3)

B'. "Forty days" (8:6)

A'. "Seven days" (8:10, 8:12)

A second chiastic structure is found in the critical events of chapters 7 and 8. This structure begins with God's command to enter the ark (7:1-10) and concludes with God's Remembrance of Noah (8:1a). Between these two "bookends" are a series of points that appear later (chapter 8) in reverse order.

A. God's Command and Noah's Response: The Entrance into the Ark (7:1-10)

B. The Beginning of the Flood: The Inundating of the Earth (7:11-16)

C. The Rising of the Waters (7:17-24)

D. God's Remembrance of Noah (8:1a)

C'. The Recession of the Waters (8:1b-5)

B'. The End of the Flood: The Drying of the Earth (8:6-14)

A'. God's Command and Noah's Response: The Exodus from the Ark(8:15-19)

So, when we put the two chiastic structures together, we see the key numbers structure is woven together with the key events structure, and both amplify the central point of the Flood account, "But God remembered Noah."