Bible Overview?
   I wanted to write a concise summary of the content of the Bible, but as I started to try I got stuck. I could see several different possible approaches, but it didn't seem right to say that any one of them was the best way to look at the big picture of the Bible. So I kept asking, "What does Scripture teach about Scripture? Does the Bible ever provide its own summary? And if so, what is it?" What I found was not only a summary of the Scriptures, but also the reason why my previous attempts had gotten stuck. Let's start by looking at how Jesus and His apostles summarized the Jewish Scriptures.

   Now [Jesus] said to them, "These are My words which I spoke to you while I was still with you, that all things which are written about Me in the Law of Moses and the Prophets and the Psalms must be fulfilled." Then He opened their minds to understand the Scriptures, and He said to them, "Thus it is written, that the Christ would suffer and rise again from the dead the third day, and that repentance for forgiveness of sins would be proclaimed in His name to all the nations, beginning from Jerusalem." (Luke 24:44-47)
   [Jesus said,] "You search the Scriptures because you think that in them you have eternal life; it is these that testify about Me;... If you believed Moses, you would believe me, for he wrote about me." (John 5:39, 46)
   But the Scripture has shut up everyone under sin, so that the promise by faith in Jesus Christ might be given to those who believe. But before faith came, we were kept in custody under the law, being shut up to the faith which was later to be revealed. Therefore the Law has become our tutor to lead us to Christ, so that we may be justified by faith. (Gal 3:22-24)
   From childhood you have known the sacred writings which are able to give you the wisdom that leads to salvation through faith which is in Christ Jesus. All Scripture is inspired by God and profitable for teaching, for reproof, for correction, for training in righteousness; so that the man of God may be adequate, equipped for every good work. (2 Tim 3:16-17)

   And now let's see what some of the authors of the New Testament have to say about their own letters.

   Therefore many other signs Jesus also performed in the presence of the disciples, which are not written in this book; but these have been written so that you may believe that Jesus is the Christ, the Son of God; and that believing you may have life in His name. (John 20:30-31)
   What was from the beginning, what we have heard, what we have seen with our eyes, what we have looked at and touched with our hands, concerning the Word of Life -- and the life was manifested, and we have seen and testify and proclaim to you the eternal life, which was with the Father and was manifested to us -- what we have seen and heard we proclaim to you also, so that you too may have fellowship with us; and indeed our fellowship is with the Father, and with His Son Jesus Christ. These things we write, so that our joy may be made complete. (1 John 1:1-4)
   My little children, I am writing these things to you so that you may not sin. And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous; and He Himself is the propitiation for our sins; and not for ours only, but also for those of the whole world. (1 John 2:1-2)
   These things I have written to you who believe in the name of the Son of God, so that you may know that you have eternal life. (1 John 5:13)
   This is now, beloved, the second letter I am writing to you in which I am stirring up your sincere mind by way of reminder, that you should remember the words spoken beforehand by the holy prophets and the commandment of the Lord and Savior spoken by your apostles. (2 Peter 3:1-2)
   Therefore, beloved, since you look for these things, be diligent to be found by Him in peace, spotless and blameless, and regard the patience of our Lord as salvation; just as also our beloved brother Paul, according to the wisdom given him, wrote to you, as also in all his letters, speaking in them of these things, in which are some things hard to understand, which the untaught and unstable distort, as they do also the rest of the Scriptures, to their own destruction. You therefore, beloved, knowing this beforehand, be on your guard so that you are not carried away by the error of unprincipled men and fall from your own steadfastness, but grow in the grace and knowledge of our Lord and Savior Jesus Christ. (2 Peter 3:14-18)
   Beloved, while I was making every effort to write you about our common salvation, I felt the necessity to write to you appealing that you contend earnestly for the faith which was once for all handed down to the saints. (Jude 3)

   The above passages reveal not only a summary of the content of the Scriptures, but also their purpose. The Law, the Pslams, the Prophets, the Gospels and the Epistles, that is, the entire Bible, directs us towards faith in the Lord and Savior Jesus Christ, and obedience to Him. To say that the Bible is "about" Christ and the gospel would be correct, but it is not enough. The Scriptures do not give a disinterested presentation of information, as if we were free to learn about them and then carry on however we pleased. The inspired authors appeal, even beg their listeners to believe in the gospel and be reconciled to God. (2 Cor 5:20) The Bible has a purpose to fulfill the Great Commission, to make disciples who obey the one true God.
   Paul says that all Scripture is "useful" to equip the man of God for every good work. Something is "useful" if it is a tool to accomplish a task. The Scriptures are a tool to lead people to trust in Christ and food to make them grow in that salvation. (1 Peter 2:2) A patient doesn't need to be taught all the features of various medical instruments in order to benefit from surgery. A thirsty person doesn't need to understand the molecular structure of water before taking a drink. And likewise God didn't design the Bible as something to be about.
   So I began to realize why I had been having so much trouble summarizing the big picture of the Bible. I was trying too much to explain the tool, rather than using the tool for its intended purpose. Yes, the Bible is an amazing collection of books, full of incredible, and incredibly interwoven, stories, themes, symbols, etc.. But that is because it has an incredibly enormous job to do, to testify to the various perfections and glories of the Risen Lord. The coherence of the Bible as a whole best shines through, not when we merely try to teach or study the Bible itself, but when we use the Bible to direct ourselves and others to follow after Christ.