When an American presidential candidate visits Israel and his key message is to encourage us to pursue a misguided war with Iran, declaring it “a solemn duty and a moral imperative” for America to stand with our warmongering prime minister, we know that something profound and basic has changed in the relationship between Israel and the United States.

My generation, born in the ’50s, grew up with the deep, almost religious belief that the two countries shared basic values and principles. Back then, Americans and Israelis talked about democracy, human rights, respect for other nations and human solidarity. It was an age of dreamers and builders who sought to create a new world, one without prejudice, racism or discrimination.

Listening to today’s political discourse, one can’t help but notice the radical change in tone. My children have watched their prime minister, Benjamin Netanyahu, kowtow to a fundamentalist coalition in Israel. They are convinced that what ties Israel and America today is not a covenant of humanistic values but rather a new set of mutual interests: war, bombs, threats, fear and trauma. How did this happen? Where is that righteous America? Whatever happened to the good old Israel?

Mr. Netanyahu’s great political “achievement” has been to make Israel a partisan issue and push American Jews into a corner. He has forced them to make political decisions based on calculations that go against what they perceive to be American interests. The emotional extortion compels Jews to pressure the Obama administration, a government with which they actually share values and worldviews, when those who love Israel should be doing the opposite: helping the American government to intervene and save Israel from itself.

Israel arose as a secular, social democratic country inspired by Western European democracies. With time, however, its core values have become entirely different. Israel today is a religious, capitalist state. Its religiosity is defined by the most extreme Orthodox interpretations. Its capitalism has erased much of the social solidarity of the past, with the exception of a few remaining vestiges of a welfare state. Israel defines itself as a “Jewish and democratic state.” However, because Israel has never created a system of checks and balances between these two sources of authority, they are closer than ever to a terrible clash.

In the early years of statehood, the meaning of the term “Jewish” was national and secular. In the eyes of Israel’s founding fathers, to be a Jew was exactly like being an Italian, Frenchman or American. Over the years, this elusive concept has changed; today, the meaning of “Jewish” in Israel is mainly ethnic and religious. With the elevation of religious solidarity over and above democratic authority, Israel has become more fundamentalist and less modern, more separatist and less open to the outside world. I see the transformation in my own family. My father, one of the founders of the state of Israel and of the National Religious Party, was an enlightened rabbi and philosopher. Many of the younger generation are far less open, however; some are ultra-Orthodox or ultranationalist settlers.

This extremism was not the purpose of creating a Jewish state. Immigrants from all over the world dreamed of a government that would be humane and safe for Jews. The founders believed that democracy was the only way to regulate the interests of many contradictory voices. Jewish culture, consolidated through Halakha, the religious Jewish legal tradition, created a civilization that has devoted itself to an unending conversation among different viewpoints and the coexistence of contradictory attitudes toward the fulfillment of the good.

The modern combination between democracy and Judaism was supposed to give birth to a spectacular, pluralistic kaleidoscope. The state would be a great, robust democracy that would protect Jews against persecution and victimhood. Jewish culture, on the other hand, with its uncompromising moral standards, would guard against our becoming persecutors and victimizers of others.

BUT something went wrong in the operating system of Jewish democracy. We never gave much thought to the Palestinian Israeli citizens within the Jewish-democratic equation. We also never tried to separate the synagogue and the state. If anything, we did the opposite. Moreover, we never predicted the evil effects of brutally controlling another people against their will. Today, all the things that we neglected have returned and are chasing us like evil spirits.

The winds of isolation and narrowness are blowing through Israel. Rude and arrogant power brokers, some of whom hold senior positions in government, exclude non-Jews from Israeli public spaces. Graffiti in the streets demonstrates their hidden dreams: a pure Israel with “no Arabs” and “no gentiles.” They do not notice what their exclusionary ideas are doing to Israel, to Judaism and to Jews in the diaspora. In the absence of a binding constitution, Israel has no real protection for its minorities or for their freedom of worship and expression.

If this trend continues, all vestiges of democracy will one day disappear, and Israel will become just another Middle Eastern theocracy. It will not be possible to define Israel as a democracy when a Jewish minority rules over a Palestinian majority between the Jordan River and the Mediterranean Sea — controlling millions of people without political rights or basic legal standing.

This Israel would be much more Jewish in the narrowest sense of the word, but such a nondemocratic Israel, hostile to its neighbors and isolated from the free world, wouldn’t be able to survive for long.

But there is another option: an iconic conflict could also present an iconic solution. As in Northern Ireland or South Africa, where citizens no longer spill one another’s blood, it will eventually become clear that many Israelis are not willing to live in an ethnic democracy, not willing to give up on the chance to live in peace, not willing to be passive patriots of a country that expels or purifies itself of its minorities, who are the original inhabitants of the land.

Only on that day, after much anguish, boycotts and perhaps even bloodshed, will we understand that the only way for us to agree when we disagree is a true, vigorous democracy. A democracy based on a progressive, civil constitution; a democracy that enforces the distinction between ethnicity and citizenship, between synagogue and state; a democracy that upholds the values of freedom and equality, on the basis of which every single person living under Israel’s legitimate and internationally recognized sovereignty will receive the same rights and protections.

A long-overdue constitution could create a state that belongs to all her citizens and in which the government behaves with fairness and equality toward all persons without prejudice based on religion, race or gender. Those are the principles on which Israel was founded and the values that bound Israel and America together in the past. I believe that creating two neighboring states for two peoples that respect one another would be the best solution. However, if our shortsighted leaders miss this opportunity, the same fair and equal principles should be applied to one state for both peoples.

When a true Israeli democracy is established, our prime minister will go to Capitol Hill and win applause from both sides of the aisle. Every time the prime minister says “peace” the world will actually believe him, and when he talks about justice and equality people will feel that these are synonyms for Judaism and Israelis.

And for all the cynics who are smiling sarcastically as they read these lines, I can only say to Americans, “Yes, we still can,” and to Israelis, “If you will it, it is no dream.”