The security forces had set up roadblocks to stop us from reaching the black township to attend a funeral for one of the thousands they had killed to protect our "security". So we had to take backroads and cross open ground. Some were intercepted and turned back, but hundreds of us white activists still made it in, to stand side by side with a mourning community rededicating itself to the fight for justice - and to make clear to them, and to our own communities, that we would resist the crimes committed in our name.

In those precious few hours of solidarity, as police helicopters circled overhead, we briefly inhabited the shared future for which we were all striving. The popping of tear-gas canisters always heralded our return to the present, and the challenges we faced to bring that future to life. That was my experience, week after week, in the apartheid South Africa of the late 1980s. And it was echoed in the experience of hundreds of Israeli activists in the West Bank village of Bilin last week.

The death of Jawaher Abu Rahmah after inhaling tear-gas fired by Israeli soldiers at a protest against the Israeli security wall that cut off the village from half of its land, might easily have passed as just another Palestinian casualty of the occupation. Her brother Baseem had been killed after being struck by a tear gas canister 18 months earlier, and local activists say 21 people have died in protests against the wall.

For Israelis, the wall stopped suicide terror. Many are indifferent to the reality on the other side. But news of Abu Rahmah's death brought hundreds of people onto the street in Tel Aviv, shutting down traffic outside the Defence Ministry in protest.

The Israeli police and judicial authorities are finding themselves dealing more frequently with dissenting Israeli Jews; just the previous week, a court had sentenced the activist Jonathan Pollak to three months in prison for his part in a bicycle protest against the blockade on Gaza. "I will go to prison wholeheartedly and with my head held high," Pollak told the judge. "It will be the justice system itself, I believe, that will need to lower its eyes in the face of the suffering inflicted on Gaza's inhabitants."

Pollak has been one of hundreds of Israelis joining Palestinian demonstrations against the Wall and Israeli settlements in East Jerusalem and the West Bank. When a South African symphony orchestra ignored the call by the Nobel Peace Prize laureate Archbishop Desmond Tutu and went to perform in Israel, they found Israeli protesters at the concert hall condemning them for ignoring Israeli apartheid in the occupied territories.

The failure of the traditional peace process and the rightward drift of Israeli politics has spurred the Israeli left out of the paralysis that followed the terror wave of the Second Intifada. Israeli academics, cultural figures and activists are calling for boycotts of settlements; soldiers who have served in occupied territories, through the "Breaking the Silence" organisation, are recounting the abuses they witnessed in the West Bank and Gaza. Israeli human rights groups are challenging the government's version of events, and young Israelis are "crossing the line" to stand alongside communities resisting occupation.

Israeli dissident groups still represent a sliver of their society, but they have the Israeli authorities worried. The Knesset is expected soon to make it a criminal offence for any Israeli to call for economic sanctions or boycotts aimed at forcing the country to change its policies. Just last week, the Knesset voted to establish a commission of inquiry into some of the dissident groups. One of the inquiry's advocates, the right-wing MK Michael Ben Ari, branded groups like Breaking the Silence as "traitors who must be persecuted at all costs", adding: "If we'll have to enact a law in the Knesset to eradicate this dangerous enemy, that is what we'll do."

Israeli human rights and dissident groups dismissed the inquiry as reminiscent of McCarthy era anti-communist witchhunts, and the liberal former Knesset Speaker Avram Burg urged such groups to refuse to testify.

The reason for the authorities' anxiety is that dissident groups undermine Israel's PR strategy of painting all criticism of its abuses as part of an anti-Semitic campaign to "delegitimise" Israel. When Israeli soldiers who served in Gaza step forward to affirm many of the allegations in the Goldstone Report (which the Israelis tried to "delegitimise"), or when Israeli activists armed with video evidence systematically challenge the IDF's account of its actions in Bilin, it becomes harder for the state to cry "anti-Semitism". Whatever their numbers, the left-wing activists make clear that there are Jews on both sides of the issue. The stated purpose of some of the activists is to use their access to the media to amplify Palestinian voices of protest, and demand that western powers not allow their own history of persecuting Jews to shame them into passivity.

A shift is already under way, as Israel's more liberal Jewish supporters in the US are finding it harder to defend, while European countries that strongly supported Israel in the face of suicide terror are increasingly impatient with Israel's insistence on expanding its settlements.

Apartheid South Africa began in the 1980s with the support of the US and Britain as an ally against communism, but as the decade drew to a close, the violent repression of township protest saw those countries forced by their electorates to isolate Pretoria. Israel may be heading down the same track. Still, the road ahead for Palestinians fighting to end the occupation and for the Israelis supporting them remains long and bitter, and increasingly dangerous as right-wing militancy in Israel grows.

But even if they cannot change the reality of the occupation, there is one reality that those Israelis going to Bilin and Sheikh Jarrah have already succeeded in changing: for thousands of young Palestinians in those areas, it will never again be true that the only Israelis they have ever known are soldiers and settlers. That, in itself, is a precious investment in a future free of hate.