Introduction

God is a God of order. He is also a God who divides. Even on the first day of creation, He divided the light from the darkness. And, He expects His servants to rightly divide His word (2Timothy 2:15Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth.
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Therefore, it should not surprise us that God has provided natural divisions in the Bible. These divisions, interestingly enough, are sevenfold. Each level of division is a subdivision of the unit above it.  

The sevenfold division has the mark of God upon it. The number seven in scripture identifies the perfect work of God. The creation of this world began with seven days (six days of creation and one day of rest). There are seven colors of the rainbow and seven notes in the major scale. Joshua marched seven times around Jericho on the seventh day. But most important for this article is Psalm 12:6The words of the LORD are pure words: as silver tried in a furnace of earth, purified seven times.
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“The words of the LORD are pure words: as silver tried in a furnace of earth, purified seven times.”

God speaks of the sevenfold purification of His Book. He introduces a seven-sealed book in the book of Revelation (Revelation 5:1And I saw in the right hand of him that sat on the throne a book written within and on the backside, sealed with seven seals.
See All...). And we see a natural (should we say providential?) sevenfold level of divisions in the Bible. The seven divisions are as follows:

Testaments

The Bible is clearly divided into two testaments. A testament is related to the idea behind a last will and testament. It refers to something received after something or someone dies. Hebrews 9:16-17 [16] For where a testament is, there must also of necessity be the death of the testator. [17] For a testament is of force after men are dead: otherwise it is of no strength at all while the testator liveth.
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“For where a testament is, there must also of necessity be the death of the testator. For a testament is of force after men are dead: otherwise it is of no strength at all while the testator liveth.” 

The “old testament” (2Corinthians 3:14But their minds were blinded: for until this day remaineth the same vail untaken away in the reading of the old testament; which vail is done away in Christ.
See All...) was in force during the time that men’s sins were covered upon the sacrifice of animals. The section of the Bible known as the Old Testament deals with this time. The “new testament” (2Corinthians 3:6Who also hath made us able ministers of the new testament; not of the letter, but of the spirit: for the letter killeth, but the spirit giveth life.
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“And as they were eating, Jesus took bread, and blessed it, and brake it, and gave it to the disciples, and said, Take, eat; this is my body. And he took the cup, and gave thanks, and gave it to them, saying, Drink ye all of it; For this is my blood of the new testament, which is shed for many for the remission of sins.”

Through His shed blood, Jesus became “the mediator of the new testament” (Hebrews 9:15And for this cause he is the mediator of the new testament, that by means of death, for the redemption of the transgressions that were under the first testament, they which are called might receive the promise of eternal inheritance.
See All...). The part of the Bible known as the New Testament records the coming of Christ to earth as a man, His sacrifice for us on the cross and the early record of His followers. 

Writings

This refers to the major sections of the Bible that are distinct as to type of writing. This division is the most difficult to define both as to title (I chose “writings”) and to exact number of them in the Bible (usually given as from 6 to 10 for the entire Bible). However, even though some may disagree as to where to make the divisions, the concept is of God. Jesus Himself accepted the standard Jewish division of the Hebrew Bible in His time. Luke 24:44And 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.
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“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.”

Notice, He speaks of the law of Moses, the prophets and the psalms. These were the writings of the Old Testament as defined at that time. Today, some Bible teachers may separate the minor prophets from the major prophets and some may not. Some may include the book of Acts with the gospels and some may not. However, the distinction of writings in scripture is very clear. Here is my personal division of the Bible into seven major sections:

• Law
• Genesis – Deuteronomy
• Five (5) books
• History (Old Testament)
• Joshua – Esther
• Twelve (12) books
• Poetry
• Job – Song of Solomon
• Five (5) books
• Prophecy (Old Testament)
• Isaiah – Malachi
• Seventeen (17) books
• Sometimes divided into Major Prophets (5 books) and Minor Prophets (12 books)
• History (New Testament)
• Matthew – Acts
• Five (5) books
• Sometimes divided into Gospels and Acts
• Epistles
• Romans – Jude
• Twenty-one (21) books
• Sometimes divided into Gentile Epistles (13 books) and Jewish Epistles (8 books)
• Prophecy (New Testament)
• Book of Revelation
• One (1) book

Books

This is the original separation between the individual books as originally written. The word Bible actually mean a collection of writings or library of books. The Apostle John refers to his prophetic work as a book in Revelation 22:10And he saith unto me, Seal not the sayings of the prophecy of this book: for the time is at hand.
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“And he saith unto me, Seal not the sayings of the prophecy of this book: for the time is at hand.”

The Bible has a total of 66 books; 39 in the Old Testament and 27 in the New Testament. Each of these books is a whole within itself and yet each book relates to the other books of the Bible.

Chapters

Chapters separate the Bible into blocks of text suitable for public reading, study or teaching. The Bible was first divided into chapters about 1250 by Cardinal Hugo for the purpose of reference in a Latin concordance. For this reason, many have questioned the validity of the chapter divisions.

Yet, the concept of chapter divisions is based on Biblical practice. The Psalms are individual songs and were separate from the beginning. In a sermon, Paul quotes from the “second psalm” (Acts 13:33God hath fulfilled the same unto us their children, in that he hath raised up Jesus again; as it is also written in the second psalm, Thou art my Son, this day have I begotten thee.
See All...). Lamentations was divided into five separate poems. Four of these five poems are 22 verses each (the number of letters in the Hebrew alphabet). Of all the chapters in the Bible, the most common length is 22 verses. It seems clear that this size of text was providentially chosen for reading, study, etc.

The Bible has a total of 1,189 chapters. The Old Testament has 929 chapters and the New Testament has 260 chapters. 

Verses

Verses separate the Bible text into lengths suitable for reference, quotation and memorization. New Testament quotations from the Old Testament set the pattern for the length of a verse. Matthew 1:22-23 [22] Now all this was done, that it might be fulfilled which was spoken of the Lord by the prophet, saying, [23] Behold, a virgin shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us.
See All... gives an example where Isaiah 7:14Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.
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“Now all this was done, that it might be fulfilled which was spoken of the Lord by the prophet, saying, Behold, a virgin shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us.”

The New Testament was first divided into verses in 1551 by Sir Robert Stephens in his Greek New Testament. In 1560, the Geneva Bible, an English translation of the Bible made by the English exiles in Geneva, divided the entire Bible into the verses that we still use today.

An old source said that the number of verses in the Bible totaled 31,173 and many to this day have quoted this number. However, this number is wrong. Also wrong is the common teaching that the middle verse in the Bible is Psalm 118:8It is better to trust in the LORD than to put confidence in man.
See All.... I have checked this myself and have had it verified by a number of sources. The Bible has 31,102 verses and the middle verses (two verses are required because of the even number of total verses) are Psalm 103:1-2 [1] Bless the LORD, O my soul: and all that is within me, bless his holy name. [2] Bless the LORD, O my soul, and forget not all his benefits:
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Words

Words distinguish between individual mental concepts. Language is made up of words and God speaks to man in words. Proverbs 30:5Every word of God is pure: he is a shield unto them that put their trust in him.
See All... teaches that “every word of God is true.” Men are warned against taking any words from the book of Revelation (Revelation 22:19And if any man shall take away from the words of the book of this prophecy, God shall take away his part out of the book of life, and out of the holy city, and from the things which are written in this book.
See All...). It is the words that are pure and preserved in Psalm 12:6-7 [6] The words of the LORD are pure words: as silver tried in a furnace of earth, purified seven times. [7] Thou shalt keep them, O LORD, thou shalt preserve them from this generation for ever.
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 “The words of the LORD are pure words: as silver tried in a furnace of earth, purified seven times. Thou shalt keep them, O LORD, thou shalt preserve them from this generation for ever.”

By one count, there are 773, 746 words in the King James Bible. This means that the average verse is approximately 25 words long. There are approximately 8,000 different words in the English Bible. The power of God in using words can be seen when this is compared with Shakespeare. He used about 25,000 different words in his writings. God said much more with fewer words. 

Letters

The last division is that of the letters. They separate between the distinct sounds which make up the words. They are important because a change in them can create a new word and meaning. Paul distinguishes between the meaning of seed and seeds in Galatians 3:16Now to Abraham and his seed were the promises made. He saith not, And to seeds, as of many; but as of one, And to thy seed, which is Christ.
See All.... Someone, I do not know who, has said that there are 3,556,480 letters in the Bible. This means that the average word has slightly less than five letters.