Christianity's god says that we are not worthy without him.

[Drich]

Oooo, looks like we are going to have some fun!

I think the answer to this lies in the function of the stories in the old testament.

where in the OT? by what you have written here it seem the 'stories' you refer to can be found in the first 5 books. Do you look beyond? are you saying the whole OT from start to finish is made up?

Unlike Christians, the Jews believed that a person's wrongdoing would be punished in this life, not in any hereafter.

Actually by the time of Christ the Jewish belief in an after life was well established. The Pharisees represented the leaders who among other things believed in an afterlife/Resurection. The Saducees (the ruling class) did not. They are the one who believed as you have outlined above. (which is why there are sad, you see?)

And if a whole people were guilty of error, the whole would be punished in this world. In part, but there are two primary verses the Pharrisees stood behind in their teaching. The first is: "Thy dead shall live, my dead bodies shall arise, awake and sing, ye that dwell in the dust, for thy dew is as the dew of light, and the earth shall bring to life the shades" (Isaiah 26:19); and the second: "And many of them that sleep in the dust of the earth shall awake, some to everlasting life, and some to reproaches and everlasting abhorrence" (Daniel 12:2).

In these two verses not only can we say that they believed as you have described in your above statement but also in a more 'christian' way, in that we are indivisually responsiable for our sins in this life. (this passage in Daniel also dispels the idea that the Jews did not believe in Hell.)

It's a cultural identity myth; it's purpose is to keep the people together by motivating them all to believe the same cultural stories. The Hebrews most likely were a strain of Semite intermixed with all the other breeds of humans occupying Canaan, and so stories evolved to make them feel special and obligated to care about that specialness. The carrot is a poor long term solution to keep a people united; the stick works much better. So they have a myth of oppression (Exodus) and of triumph (Joshua) and tales of bad, fallen away Jews being punished, and good, united Jews prospering.

there are many others examples dotting Jewish history upto the time of Christ are you saying all of them were made up?

Just as in biological evolution, those Canaanite Jews who developed such myths stayed together and by staying together, continued the myths; those who didn't, weren't able to stay together as a people, even though they likely had their stories too — their stories didn't exert a force to keep them together as a culture, retelling the stories over and over again.

Actually there was a great divide after the reign of Solomon in the Jews (2kings) where there were even acts of civial war amongst the 12 tribes, not to mention many instances of defeat slavery and occupation. How does this figure into your Darwinian type model? where is was unity and safty in numbers that saved these people's culture from being assimilated into their many conquers.

So the ultimate answer is that, from the perspective of social psychology, myths of redemption and creating the idea that by being united you can be saved from something, those memes worked better in terms of perpetuating themselves by encouraging the hearer to a) think of his group membership as valuable (redemptive), and b) encouraged him to repeat and celebrate those stories. Other memes simply didn't succeed at keeping themselves alive in a cohesive, unified culture in the same way.

But the Jews have always been divided from the time of David and beyond. They rarly come together, when they do God blesses them and they do great things but eventually infighting and pride wins out and division sets in again.
There is no reason these twelve tribes should have retained their coheasion for as long as they have. But they have, which is a testament to God's covenant with Abraham.