I find the same to be true of the book of 1st Chronicles. This book covers a lot of the same territory as 1st and 2nd Kings and 1st and 2nd Samuel, but this time the primary focus is on the life of David. This book gives us the the genealogy of David for instance. This line of history takes us all the way back to the dawn of man, listing the sons and descendants of Adam -- Able, Seth, Enosh, Kenan, Mahalalel. But the focus of this genealogy is on the descendants of Seth. Note: Notice that there is no mention of Cain, this book is only concerned with the line of Seth. Here is our first example of the principle of exclusion.
Okay so this genealogy first lasers in on Seth, then Enoch, Noah, and then his three sons, Shem, Ham, and Japheth. From there the spotlight shifts to Shem, then follows Abraham and his family. Then we see the exclusion process again with the absence of Ishamael, instead focusing on Issac's twelve sons who became the fathers of the twelve tribes of Israel. From there the view narrows even further as the tribes of Judah and Levi are selected, to include the tribes of the king and the priestly line. From the line of Judah we see the thread that precludes David, and in Levi we see the line that moves forward from Aaron, the first of the priests of Israel, then to all the priests who were prominent in the time of David.
So the question is raised, why does the Scripture exclude men and women, tribes, countries and nations to focus on a rather small slice of humanity that includes the individuals listed above?
I think first of all we have to acknowledge the foundational answer given by the Bible, “For my thoughts are not your thoughts, neither are your ways my ways,” declares the Lord. “As the heavens are higher than the earth, so are my ways higher than your ways and my thoughts than your thoughts." (Isaiah 55:8-9) Recognizing that this can seem like a theological copyout but the bottom line is there are just some things that will remain unknowable. We, as humans, are incapable of understanding the will, and motivation of all the God chooses to do.
But that doesn't mean that God has left us with no clues into His character and why He wills as He wills, chooses who He chooses. In fact, He makes it crystal clear why certain people are included and others are not.
We see in not only this book but throughout all scripture that there is always one principle that God follows in this process of selectivity. He seeks out people with an obedient heart. When God finds such a person, all the native disability of that person is canceled out and he or she is immediately made an effectual instrument for the working of God in human history. When God excludes a name, it is always on the basis of a disobedient heart. This is the measuring stick for all men, regardless of race, rank, ancestry or privilege of any kind. Wherever there is an obedient heart God begins a new work in and through that person. Wherever prolonged disobedience occurs, that work is stopped until there is repentance or judgement. You can trace this principle throughout this entire genealogy.
And if you are thinking that this is a principle that only exists in the Old Testament, check out this translation of John 14:15 in The Message. Jesus said, “If you love me, show it by doing what I’ve told you." God is not looking for just our sacrifices, our virtues, and our talents, He is more greatly moved by our obedience. "You do not delight in sacrifice, or I would bring it; you do not take pleasure in burnt offerings. My sacrifice, O God, is[a] a broken spirit; a broken and contrite heart you, God, will not despise." (Psalm 51:16-17)
Obedience is the straw that stirs the heart of God. He proves that in both the Old Testament and the New Testament of the Bible. Exclusion is a demonstration of the heart and grace of God, showing us the importance of obedience and the impact of disobedience in our relationship with Him. This does not imply that obedience is the key to our salvation, but it is an important part of our sanctification.
In closing, "For it is by grace you have been saved, through faith—and this is not from yourselves, it is the gift of God— not by works, so that no one can boast. For we are God’s handiwork, created in Christ Jesus to do good works, which God prepared in advance for us to do." (Ephesians 2: 8-10)