Psalms 119:89
Forever, O Lord,
Your word is settled in heaven.

Think about the author of a book. He or she has an idea of a beginning and an ending. In the case of a series, several books are involved to get to the ending.
Many book series continue in a chronological order with characters in later books introduced in the first.
Skipping the first book of the series leaves a hole in the story if a character shows up in the fifth book.
You may not know the ending by reading the first chapter or the fifth book in a ten book series.
You must read the entire book or series to know the beginning, the plot, the climax, and the ending.

The Bible is not one book but contains sixty-six books. You cannot read the start with the middle and understand the beginning. You cannot just read the beginning and know the ending. You cannot know the entire truth of God’s word by reading only part.
The Psalmist is correct – God’s word is settled in heaven. God knew the beginning, the middle, and the end before Moses began writing Genesis.
Therefore, you must take His entire word to understand what is settled in heaven.