Alright then. This is a pretty big topic so I'll try to keep it focused and comprehensible. This will be an overview of the history of God's dealings with his people in order to give the background to the events around the time of Christ's incarnation. This is a summary of the historical aspect of the Old Testament.
In the beginning, God created man (and woman). He created us as the final piece of the universe. We were the last thing that needed to be made for creation to be good. When God created us, he gave us the universe to manage and rule (wisely) as His stewards. We were also not to be like automata but to become part of God's family. Another way of looking at it is God allows His creation to participate in His plans. In this case God allowed humans to participate in His dominion over creation. Accordingly, unlike most other creations, we were given free will. A rock cannot help but to fall due to the law of gravity. An animal does what its instincts tell it. But we can choose not to obey the law of humanity even to the point of self-destruction. The law (Natural Law) is the one that governs the proper operation of this thing called "man." We can choose to act in a way that makes us bad at being human. And that is precisely what we did. God foresaw this and had already incorporated this into His plan.
Fast forward. Humans have covered the Earth but so has sin. People were forgetting their creator. God chose one person out of everyone to be His ambassador on Earth. This man's name was Abram (later Abraham). He was to give rise to a nation whose purpose was to be the means of reconciliation between the whole world and God. A chosen people: not chosen because there was anything special about Abraham or out of favouritism, but chosen for a higher and more difficult path. This nation would experience many hardships but would also be privileged with being the instrument of God's plan. To that end, they would need instruction and refining. God continued this arrangement with his son Issac and grandson Jacob. At the end of Genesis, God preserves this nation by bringing it into Egypt.
>EXODUS - DEUTERONOMY
This nation is now being harshly dealt with by the reigning pharaoh. God selects Moses to be the one to lead them out of Egypt. Afterwards, He appears to them on Mt Sinai. Moses is again the one to go up and mediate between God and man. God hands down Moses a law most famously expressed in the ten commandments. At the head is the commandment that thou shalt have no other gods before me. Remember this is a people who was chosen to be God's light in the world so it's important that they actually do that. No sooner does Moses descend the mountain than he discovers that the people are already worshipping other gods. Right after God had granted a miraculous parting of the Red Sea so they could escape the Egyptian army. The rest of these four books detail the wanderings through the desert, the census of people and the elaboration of the law. The purpose of much of the law was to keep God's people as something that could legitimately be called God's people. To keep them visibly separate from other nations and as a way to guard them from relapsing until such time as God's plan is realised when the purpose of the law would be fulfilled. It's hard to light up a room if you hide the lamp under your bed. It's hard to bring light to the nations if you hide it and are not visibly different to the peoples around you. This part of the law is different to the Natural Law I talked about earlier.
This book deals with the conquest of Canaan. It narrates the establishment of a defined place where God's people could be nurtured into fruition and where the events of the Old Testament would largely take place. It's about the beginnings of the fight back against darkness in the expressly political sphere.
God's people are now living in the Holy Land but they have again backslid. Judges can be pretty much summarised like this:
The people are wallowing in moral decay internally and political strife externally.
God raises up a judge to lead His people.
The judge defeats the cause of external strife and restores the people to holiness.
The judge dies.
The people backslide.
Repeat many times.
Judges is a perfect encapsulation of the entire Old Testament and indeed the story of humanity in general. Throughout history we see again and again long, slow periods of decline punctuated by sharp periods of restoration. Throughout this, it is important to keep in mind that God is restoring humanity. That means that we ourselves must struggle through this process in which repeated failures are an inevitable part. Like a teacher with his student, God means to teach us how to stand on our own two feet and not be babies anymore.
>KINGS 1-2 CHRONICLES 1-2
These books deal with the kings of the united kingdom and the divided kingdoms of Judah and Israel. A lot of it is about the tension between kings who want to do evil and God's prophets who warn against this and pronounce judgement on the wicked.
These talk about the specific prophets they are named after. Some of them are sent to other lands such as Edom or Assyria. Remember that the point of God's people is to bring light to the whole world. It's not about "these are the only people I like and everyone else can stuff it." Many of the prophecies given directly concern Jesus as more of God's character and plan is revealed to Israel and Judah over the centuries. God promises a messiah who will come and restore God's people. Most of the prophets were killed because people don't like hearing the truth about themselves.
>THE NEW TESTAMENT
Suddenly one day it happens. God Himself descends to Earth as the god-man Jesus. You would think God's people, after centuries of special care and raising, would be thrilled about it. Many of them were not. In earlier times, understanding of God was dim and concrete metaphors had to be used to teach people. Military, political and financial success were all used as metaphors for the internal transformation of humanity. For example, in Judges the political restoration and moral restoration are linked so that you can understand one by the other. As time went on, understanding of God remained dim but improved enough that we can talk about the transformation without reference to such things. The problem with the Pharisees and many others (not just the Pharisees) is that they took completely the wrong message from this. They were convinced that the messiah was to enact a political restoration and rule over the other nations. No doubt the Pharisees (who were a faction of the priestly class) had in mind that they would rise to power alongside. Perhaps in a sort of advisory role or "intelligentsia?" Hmm I wonder where I've heard that before...
In actual fact, the messiah was to restore God's people morally speaking and, through them, bring the entire world into the fold. The things they took pride in - lineage, the law - were just tools to God to bring about this end. With Jesus, they were no longer necessary. They had fulfilled their purpose. Many people, who we will now call Jews, rejected their own God and messiah. The same city that killed the prophets God had sent, killed His Son in the most outrageous act in history. In the words of the reproaches sung on Easter Friday:
O my people,
What have I done to you?
How have I offended you?
There is an exceptionally good version of it you can read about half way down this page. Just ctrl-f "The Reproaches."
God's people continued through and spread throughout the world and brought in people from all nations as was always the plan from before the world was made. The Jews, on the other hand, remained bitter and eternally butthurt that they can't use God to advance their own selfish desires of power and domination. They rejected God because, in the end, they did not want that kind of god. They wanted a god they could use for their own ends. As a final act to make things perfectly clear, God sent the Romans to destroy the physical temple in Jerusalem which was the centrepiece of religion and absolutely necessary for the proper worship of God under the law. The Jews still rejected God showing that even when their toys are taken away, they would still rather throw a tantrum than accept reality. Centuries after that, they made up a bunch of pilpul as a cope for the fact that their sins can't be atoned for without a temple under the law. This is Talmudic Judaism. It is utterly different to what people practised before Christ because it has to be.
I have deliberately avoided the use of the word Jew until the end to make the point that we Christians are God's people. Not a replacement people because the originals weren't good enough: the same people. Membership is not reckoned by ancestry but by faith. The people called "Jews" nowadays call themselves "God's people" in arrogance and falseness because they are precisely the ones who rejected God. I don't really care about the whole "Jews are actually from Ukraine" business because this is the important bit. In practice, the word Jew is used to refer to
>the genetic descendants of Abraham and the community he led
>the people Moses led out of Egypt
>the people living in Israel and Judah
>the people living in Judaea at the time of Christ
>The people who rejected Christ at the time
>The people who call themselves Jews and reject God today.
How much genetic continuity exists between the first and the last is irrelevant in the face of the fact that the latter reject the God of the former and so undermine everything they say about themselves. We never should have allowed them to keep that word because it's caused nothing but confusion. Calling Christianity "Jewish" is like calling Britain "American." Judaism (as we popularly understand the meaning today) is under 2000 years old. Christianity is ancient because God's people looked forward to the time when Christ would come (christ is Greek for the Hebrew messiah) as foretold by God's prophets.