In answering the question at hand, I think it is imperitive to make it known upfront that the Bible is NOT a single book, but rather a collection of letters, books, and other writings all compiled into a single canon. What that means is that rather than there being a singular purpose, we would do well to look for multiple and oftentimes differing purposes from writing to writing.
If we take for instance, the Torah and the OT books of history (Joshua - Esther), we find a supposed history of A.N.E. Israel and Judah along with what some would call propaganda employed to present those people as being special people chosen by the world's true master and creator. Within that history we can find what those people's governing arrangement as well as their laws and constitution were. In the end we see a warring people that were never able to find lasting peace, prosperity, and stability one would expect in a people chosen by the world's true master and creator. China is never mentioned.
If we take a look at the other OT writings for the most part we find GDR (God Dick Riding), prophesy of blessing or calamity, promises of peace, joy, and inheritance (land/region ownership), and proclamations of the utter failure of the chosen people and the promises of messiah figures culminating in one of those figure becoming king of a kingdom that would stand forever (actually for ages of ages since eternity or the concept of forever is no where clearly expressed in the OT writings). Again, China is never mentioned and all of the writings are from the perspective of and directed towards the supposed decendants of a warlord originally named Abram that had a son of promise he called Isaac.
We get to the NT and we see that Jewish writings continue, only now what is written is from the perspective of Jews that claim to have found the culminating messiah figure and have been commissioned to share this figure's story and message to the whole world as they knew it starting of course with Jerusalem. The suposed decendants of Isaac that did not share the perspective of the NT writers had beef and objected to the NT writers and charactor's proclamations and persecuted them by turning authorities on the new sect of Jews and/or running them out of Judea causing the message proclaimed by the new sect of Jews to be spread to other areas. Again, no mention of China being included.
The Bible concludes with a series of letters supposedly written by some of the individuals who were being persecuted by the old school Jews and Roman authorities (The enemy of my enemy is my enemy, go figure that!). These letters tnded to emphasize the need to persevere through the difficulties because the promises made by the culminating messiah figure would soon be fulfilled and that they would then be rewarded with life and some would even be given positions of power and judgment within the kingdom of the culminating messiah figure. The were instructed to continue in the faith they had recently acquired, separate themselves from those that did not share in their faith as those that did not share in their faith were in danger of God's or the culminating messiah's (maybe they are one and the same?) judgment, and to love and share with one another.
Then the writings end, and here we stand living centuries after the supposed events happened and promises were given and many of our contempories as well as us at some point in the past may have looked at the writings in the Bible wholeheartedly believing that there was apurpose therein specifically for us. REALLY? REALLY? No, REALLY?
The best guess at finding purposes would be to say that the history portion was written in all likelihood to give a collection of sementic former Babylonian captives a history that unified them and gave them a sense of value and purpose.
The second part of the OT was likely what I call some 'act right'. It was written to try to get the people to stay in line under the 'proper' authority and to help in an attempt at keeping these people as a strong unified group in hopes that these people would have an enduring position of power and influence in the world.
Parts of the NT may have been written to say that since much of the OT went to $hi+ in regards to reality of the position the suposedly chosen people of the Master were in and what they had expected, that the Master and Creator would use their gene pool to give the whole world a king and conquer not only the world, but even death itself! The rest of the NT basically says, "yep that (the beginning of this paragraph) is true and everything it said is gonna happen real soon. Just watch!"
And people have been watching ever since........................
ps. I'm told that now, even a few people in China are watching!