My mother recently met an old friend, they had a little chat, but then the next day she got an e-mail from her former friend saying she couldn't talk to her any more because of what Israel is doing in Gaza.
My mother is 90 and lives in London. She has absolutely no influence over Israeli policy and certainly bears no responsibility for it. You might as well blame her for the death of Jesus. Yet there is this notion in certain circles that Jews are collectively responsible for the fate of the Palestinians. Fortunately, perhaps, the same people have no such claims about our responsibility for our own fate. If my mother gets bombed, these same people will consider it entirely her own problem.
The idea of collective Jewish responsibility is not a purely antisemitic thing. A recent article in the New York Times (A Yearning for Solidarity Tangles Public Life by Ethan Bronner) commented on the sense of mutual responsibility that exists in Israel and suggested it was a potential problem in Israeli politics.
Actually I rather like it, its what made our demonstrations in support of the welfare state both highly successful and completely non-violent: the biggest demonstration, with 350,000 (5% of Israelis) in attendance was held in the most expensive square in Tel Aviv, where all the top designer stores have branches, and not a single storefront was broken. That could never have happened in England. It is also why the Israeli government released hundreds of dangerous men in return for one minor soldier. Half the country now regards Gilad Shalit as their son. If Hamas didn't give him post-traumatic stress disorder, then the queues of people trying to get a look at him (after years of total isolation) probably will.
I think all this mutual responsibility is related to the Bible. The Jewish God wasn't into individual responsibility. The Jews were chosen to deliver a message and they had to do it as a collective. In the Biblical narrative, if some do wrong, we all get punished. For example, in Exodus 32 (9), the Israelites built and worshipped a golden calf while Moses was up Mount Sinai "I have seen these people,” the LORD said to Moses, “and they are a stiff-necked people. Now leave me alone so that my anger may burn against them and that I may destroy them.” Moses then argues with God and gets the punishment reduced, thus launching thousands of Jewish lawyers on the world, all well capable of arguing with God.
That's why Jews aren't required to believe in God: Rabbinical Judaism requires you to follow the commandments; we can be atheists so long as we keep the Sabbath, circumcise boys and fast on Yom Kippur. Otherwise we all get it. Incidentally the converse also applies: maltreat the Jews and God punishes you collectively.
The Christians developed a different system, one based on individual responsibiity. Christians, especially protestants, can improvise their prayers and are held to account on a personal basis. But all too many fail to apply an individual-based moral system to Jews.