Inside the First Congregational Church of Berkeley, the Californian audience had been struck silent. Dennis Bernstein, the Jewish host of KPFA Radio's Flashpoint current affairs programme, was reading some recent e-mails that he had received from Israel's supporters in America. Each one left the people in the church – Muslims, Jews, Christians – in a state of shock. "You mother-fucking-asshole-self-hating Jewish piece of shit. Hitler killed the wrong Jews. He should have killed your parents, so a piece of Jewish shit like you would not have been born. God willing, Arab terrorists will cut you to pieces Daniel Pearl-style, AMEN!!!"

Bernstein's sin was to have covered the story of Israel's invasion of Jenin in April and to have interviewed journalists who investigated the killings that took place there – including Phil Reeves and Justin Huggler of The Independent – for his Flashpoint programme. Bernstein's grandfather was a revered Orthodox Rabbi of international prominence but neither his family history nor his origins spared him. "Read this and weep, you mother-fucker self-hating Jew boy!!!" another e-mail told Bernstein. "God willing a Palestinian will murder you, rape your wife and slash your kids' throats." Yet another: "I hope that you, Barbara Lubin and all other Jewish Marxist Communist traitors anti-American cop haters will die a violent and cruel death just like the victims of suicide bombers in Israel." Lubin is also Jewish, the executive director of the Middle East Children's Alliance, a one-time committed Zionist but now one of Israel's fiercest critics. Her e-mails are even worse.

Indeed, you have to come to America to realise just how brave this small but vocal Jewish community is. Bernstein is the first to acknowledge that a combination of Israeli lobbyists and conservative Christian fundamentalists have in effect censored all free discussion of Israel and the Middle East out of the public domain in the US. "Everyone else is terrified," Bernstein says. "The only ones who begin to open their mouths are the Jews in this country. You know, as a kid, I sent money to plant trees in Israel. But now we are horrified by a government representing a country that we grew up loving and cherishing. Israel's defenders have a special vengeance for Jews who don't fall in line behind Sharon's scorched-earth policy because they give the lie to the charge that Israel's critics are simply anti-Semite."

Adam Shapiro is among those who have paid a price for their beliefs. He is a Jew engaged to an American-born Palestinian, a volunteer with the International Solidarity Movement who was trapped in Yasser Arafat's headquarters in the spring while administering medical aid. After telling CNN that the Sharon government was acting like "terrorists" while receiving $3bn a year in US military aid, Shapiro and his family were savaged in the New York Post. The paper slandered Shapiro as the "Jewish Taliban" and demeaned his family as "traitors". Israeli supporters publicised his family's address and his parents were forced to flee their Brooklyn home and seek police protection. Shapiro's father, a New York public high-school teacher and a part-time Yeshiva (Jewish day school) teacher, was fired from his job. His brother receives regular death threats.

Israel's supporters have no qualms about their alliance with the Christian right. Indeed, the fundamentalists can campaign on their own in Israel's favour, as I discovered for myself at Stanford recently when I was about to give a lecture on the media and the Israeli-Palestinian conflict, part of a series of talks arranged largely by Jewish Americans. A right-wing Christian "Free Republic" outfit posted my name on its website, and described me as a "PLO butt-kisser" and asked its supporters to "freep" my lecture. A few demonstrators turned up outside the First United Methodist Church in Sacramento where I was to speak, waving American and Israeli flags. "Jew haters!" they screamed at the organisers, a dark irony since these were non-Jews shrieking their abuse at Jews.

They were also handing out crudely printed flyers. "Nothing to worry about, Bob," one of my Jewish hosts remarked. "They can't even spell your name right." True. But also false. "Stop the Lies!" the leaflet read. "There was no massacre in Jenin. Fiske [sic] is paid big bucks to spin [lie] for the Arabs..." But the real lie was in that last sentence. I never take any payment for lectures – so that no one can ever claim that I'm paid to give the views of others. But the truth didn't matter to these people. Nor did the content of my talk – which began, by chance, with the words "There was no massacre" – in which I described Arafat as a "corrupt, vain little despot" and suicide bombings as "a fearful, evil weapon". None of this was relevant. The aim was to shut me up.

Dennis Bernstein sums it up quite simply: "Any US journalist, columnist, editor, college professor, student-activist, public official or clergy member who dares to speak critically of Israel or accurately report the brutalities of its illegal occupation will be vilified as an anti-Semite." In fact, no sooner had Bernstein made these remarks than pro-Israeli groups initiated an extraordinary campaign against some of the most pro-Israeli newspapers in America, all claiming that The New York Times, the Los Angeles Times and the San Francisco Chronicle were biased in their coverage of the Middle-East conflict. Just how The New York Times – which boasts William Safire and Charles Krauthammer, those giants of pro-Israeli bias, among its writers – could be anti-Israeli is difficult to see, although it is just possible that, amid its reports on Israel's destruction in the West Bank and Gaza, some mildly critical comments found their way into print. The New York Times, for example, did report that Israeli soldiers used civilians as human shields – though only in the very last paragraph of a dispatch from Jenin.

None the less, the campaign of boycotts and e-mails got under way. More than 1,000 readers suspended their subscriptions to the Los Angeles Times, while a blizzard of e-mails told pro-Israeli readers to cancel their subscription to The New York Times for a day. On the East Coast, at least one local radio station has lost $1m from a Jewish philanthropist while other stations attempting to cover the Middle East with some degree of fairness are said to have lost even more. When the San Francisco Chronicle published a four-page guide to the conflict, its editors had to meet a 14-member delegation of local Jewish groups to discuss their grievances.

According to Michael Futterman, who chairs the Middle East strategy committee of 80 Bay Area synagogues, Jewish anger hit "boiling point" when the Chronicle failed to cover a pro-Israeli rally in San Francisco. Needless to say, the Chronicle's "Readers' Representative", Dick Rogers, published a grovelling, self-flagellating apology. "The paper didn't have a word on the pro-Israel rally," he wrote. "This wasn't fair and balanced coverage." Another objection came from a Jewish reader who objected to the word "terror" being placed within inverted commas in a Chronicle headline that read "Sharon says 'terror' justifies assault". The reader's point? The Chronicle's reporting "harmonises well with Palestinian propaganda, which tries to divert attention from the terrorist campaign against Israel (which enjoys almost unanimous support among Palestinians, all the way from Yasser Arafat to the 10-year-old who dreams of blowing himself up one day) and instead describes Israel's military moves as groundless, evil bullying tactics."

And so it goes on. On a radio show with me in Berkeley, the Chronicle's foreign editor, Andrew Ross, tried to laugh off the influence of the pro-Israeli lobby – "the famous lobby", he called it with that deference that is half way between acknowledgement and fear – but the Israeli Consul General Yossi Amrani had no hesitation in campaigning against the Chronicle, describing a paper largely docile in its reporting of the Middle East as "a professionally and politically biased, pro-Palestinian newspaper".

The Chronicle's four-page pull-out on the Middle East was, in fact, a soft sell. Its headline – "The Current Strife Between The Israelis And The Palestinians Is A Battle For Control Of Land" – missed the obvious point: that one of the two groups that were "battling for control of the land" – the Palestinians – had been occupied by Israel for 35 years.

The most astonishing – and least covered – story is in fact the alliance of Israeli lobbyists and Christian Zionist fundamentalists, a coalition that began in 1978 with the publication of a Likud plan to encourage fundamentalist churches to give their support to Israel. By 1980, there was an "International Christian Embassy" in Jerusalem; and in 1985, a Christian Zionist lobby emerged at a "National Prayer Breakfast for Israel" whose principal speaker was Benjamin Netanyahu, who was to become Israeli prime minister. "A sense of history, poetry and morality imbued the Christian Zionists who, more than a century ago, began to write, plan and organise for Israel's restoration," Netanyahu told his audience. The so-called National Unity Coalition for Israel became a lobbying arm of Christian Zionism with contacts in Congress and neo-conservative think-tanks in Washington.

In May this year, the Israeli embassy in Washington, no less, arranged a prayer breakfast for Christian Zionists. Present were Alonzo Short, a member of the board of "Promise Keepers", and Michael Little who is president of the "Christian Broadcasting Network". Event hosts were listed as including those dour old Christian conservatives Jerry Falwell and Pat Robertson, who once financed a rogue television station in southern Lebanon which threatened Muslim villagers and broadcast tirades by Major Saad Haddad, Israel's stooge militia leader in Lebanon. In Tennessee, Jewish officials invited hundreds of Christians to join Jewish crowds at a pro-Israel solidarity rally in Memphis.

On the face of it, this coalition seems natural. The Jewish Anti-Defamation League felt able to run an ad that included an article by a former Christian coalition executive director Ralph Reed, headlined "We People of Faith Stand Firmly With Israel". Christians, Reed claimed, supported Israel because of "their humanitarian impulse to help and protect Jews, a shared strategic interest in democracy in the Middle East and a spiritual connection to Israel".

But, of course, a fundamental problem – fundamental in every sense of the word – lies behind this strange partnership. As Uri Avnery, the leader of Gush Shalom, the most courageous Israeli peace group, pointed out in a typically ferocious essay last month, there is a darker side to the alliance. "According to its [Christian Zionist] theological beliefs, the Jews must congregate in Palestine and establish a Jewish state on all its territory" – an idea that would obviously appeal to Ariel Sharon – "so as to make the Second Coming of Jesus Christ possible." But here comes the bad bit. As Avnery says, "the evangelists don't like to dwell openly on what comes next: before the coming [of the Messiah], the Jews must convert to Christianity. Those who don't will perish in a gigantic holocaust in the battle of Armageddon. This is basically an anti-Semitic teaching, but who cares, so long as they support Israel?"

The power of the Israeli lobby in the United States is debated far more freely in the Israeli press than in American newspapers or on US tele- vision. There is, of course, a fine and dangerous line between justified investigation – and condemnation – of the lobby's power, and the racist Arab claim that a small cabal of Zionists run the world. Those in America who share the latter view include a deeply unpleasant organisation just along the coast from San Francisco at Newport Beach known as the "Institute for Historical Research". These are the Holocaust deniers whose annual conference last month included a lecture on "death sentences imposed by German authorities against German soldiers... for killing or even mistreating Jews". Too much of this and you'd have to join the American Israel Public Affairs Committee – AIPAC – to restore your sanity. But the Israeli lobby is powerful. In fact, its influence over the US Congress and Senate calls into question the degree to which the American legislature has been corrupted by lobby groups. It is to an Israeli voice – Avnery again – that Americans have to turn to hear just how mighty the lobby has become. "Its electoral and financial power casts a long shadow over both houses of the Congress," Avnery writes. "Hundreds of Senators and Congressmen were elected with the help of Jewish contributions. Resistance to the directives of the Jewish lobby is political suicide. If the AIPAC were to table a resolution abolishing the Ten Commandments, 80 Senators and 300 Congressmen would sign it at once. This lobby frightens the media, too, and assures their adherence to Israel."

Avnery could have looked no further than the Democratic primary in Alabama last month for proof of his assertion. Earl Hilliard, the five-term incumbent, had committed the one mortal sin of any American politician: he had expressed sympathy for the cause of the Palestinians. He had also visited Libya several years ago. Hilliard's opponent, Artur Davis, turned into an outspoken supporter of Israel and raised large amounts of money from the Jewish community, both in Alabama and nationwide. The Israeli newspaper Ha'aretz noted that among the names of the first list of contributors to Davis's campaign funds were "10 Cohens from New York and New Jersey, but before one gets to the Cohens, there were Abrams, Ackerman, Adler, Amir, Asher, Baruch, Basok, Berger, Berman, Bergman, Bernstein and Blumenthal. All from the East Coast, Chicago and Los Angeles. It's highly unlikely any of them have ever visited Alabama..." The Jewish newspaper Forward – essential reading for any serious understanding of the American Jewish community – quoted a Jewish political activist following the race: "Hilliard has been a problem in his votes and with guys like that, when there's any conceivable primary challenge, you take your shot." Hilliard, of course, lost to Davis, whose campaign funds reached $781,000.

The AIPAC concentrates on Congress while the Conference of Presidents of Major American Jewish Organisations (CPMAJO), made up of the heads of 51 Jewish organisations, concentrates on the executive branch of the US government. Every congressman knows the names of those critics of Israel who have been undone by the lobby. Take Senator J William Fulbright, whose 1963 testimony to the Senate Foreign Relations Committee detailed how five million tax-deductable dollars from philanthropic Americans had been sent to Israel and then recycled back to the US for distribution to organisations seeking to influence public opinion in favour of Israel; this cost him the chance of being Secretary of State. He was defeated in the 1974 Democratic primary after pro-Israeli money poured into the campaign funds of his rival, Governor Dale Bumpers, following a statement by the AIPAC that Fulbright was "consistently unkind to Israel and our supporters in this country". Paul Findley, who spent 22 years as a Republican congressman from Illinois, found his political career destroyed after he had campaigned against the Israeli lobby – although, ironically, his book on the subject, They Dare to Speak Out was nine weeks on The Washington Post bestseller list, suggesting that quite a number of Americans want to know why their congressmen are so pro-Israeli.

Just two months ago, the US House of Representatives voted 352 to 21 to express its unqualified support for Israel. The Senate voted 94 to two for the same motion. Even as they voted, Ariel Sharon's army was continuing its destructive invasion of the West Bank. "I do not recall any member of Congress asking me if I was in favour of patting Israel on the back..." James Abu Rizk, an Arab-American of Lebanese origin, told the Arab-American Anti-Discrimination Committee afterwards. "No one else, no average American, has been asked either. But that is the state of American politics today... The votes and bows have nothing to do with the legislators' love for Israel. They have everything to do with the money that is fed into their campaigns by members of the Israeli lobby. My estimate is that $6bn flows from the American Treasury to Israel each year." Within days, 42 US governors turned up in Sacramento to sign declarations supporting Israel. California governor Gray Davis and New York governor George Pataki – California has the largest Jewish population of any state except New York – arranged the meeting.

Sometimes the support of Israel's loyalists in Congress turns into farce. Tom Delay – reacting to CNN founder Ted Turner's criticism of Israel – went so far out of his way to justify Israeli occupation of the West Bank that he blurted out on MSNBC television that the Palestinians "should become citizens" of Israel, an idea unlikely to commend itself to his friend Ariel Sharon. Texas Republican Richard Armey went the other way. "I'm content to have Israel grab the entire West Bank. I happen to believe the Palestinians should leave... to have those people who have been aggressors against Israel retired to some other area." Do the people of Texas know that their representative is supporting "ethnic cleansing" in the Middle East? Or are they silent because they prefer not to speak out?

Censorship takes many forms. When Ishai Sagi and Ram Rahat-Goodman, two Israeli reserve soldiers who refused to serve in the West Bank or Gaza, were scheduled to debate their decision at Sacramento's Congregation B'nai Israel in May, their appearance was cancelled. Steve Meinrath, who is chairman of the Israel Affairs Committee at B'nai Israel, remarked bleakly that "intimidation on the part of certain sectors of the community has deprived the entire community of hearing a point of view that is being widely debated in Israel. Some people feel it's too dangerous..."

Does President Bush? His long-awaited Middle-East speech was Israeli policy from start to finish. A group of Jewish leaders, including Elie Wiesel and Alan Dershowitz – who said recently that the idea of executing the families of Palestinian suicide bombers was a legitimate if flawed attempt at finding a balance between preventing terrorism and preserving democracy – and the AIPAC and CPMAJO heads all sent clear word to the President that no pressure should be put on Israel. Wiesel – whose courage permeates his books on the Holocaust but who lamentably failed to condemn the massacre of Palestinian refugees in Beirut in 1982 at the hands of Israel's Lebanese allies, said he felt "sadness", but his sadness was "with Israel, not against Israel" because "after all the Israeli soldiers did not kill" – took out a full page in The New York Times. In this, he urged Bush to "please remember that Ariel Sharon, a military man who knows the ugly face of war better than anyone, is ready to make 'painful sacrifices' to end the conflict." Sharon was held "personally responsible" for the massacre by Israel's own commission of inquiry – but there was no mention of that from Wiesel, who told reporters in May that he would like to revoke Arafat's Nobel prize.

President Bush was not going to oppose these pressures. His father may well have lost his re-election because he dared to tell Israel that it must make peace with the Arabs. Bush is not going to make the same mistake – nor does brother Jeb want to lose his forthcoming governorship election. Thus Sharon's delight at the Bush speech, and it was left to a lonely and brave voice – Mitchell Plitnick of the Jewish Voice for Peace – to state that "few speeches could be considered to be as destructive as that of the American President... Few things are as blinding as unbridled arrogance."

Or as vicious as the messages that still pour in to Dennis Bernstein and Barbara Lubin, whose Middle East Children's Alliance, co-ordinating with Israeli peace groups, is trying to raise money to rebuild the Jenin refugee camp. "I got a call the other day at 5am," Bernstein told me. "This guy says to me: 'You got a lot of nerve going and eating at that Jewish deli.' What comes after that?" Before I left San Francisco, Lubin showed me her latest e-mails. "Dear Cunt," one of them begins, "When we want your opinion you fucking Nazi cunt, we will have one of your Palestinian buddies fuck it [sic] of you. I hope that in your next trip to the occupied territories you are blown to bits by one of your Palestinian buddies [sic] bombs." Another, equally obscene, adds that "you should be ashamed of yourself, a so-called Jewish woman advocating the destruction of Israel".

Less crude language, of course, greeted President Bush's speech. Pat Robertson thought the Bush address "brilliant". Senator Charles Schumer, a totally loyal pro-Israeli Democrat from New York, said that "clearly, on the politics, this is going to please supporters of Israel as well as the Christian coalition types". He could say that again. For who could be more Christian than President George W Bush?