I’ve written a series of columns from Israel in the past two weeks because I believe that if Secretary of State John Kerry brings his peace mission to a head and presents the parties with a clear framework for an agreement, Israel and the Jewish people will face one of the most critical choices in their history. And when they do, all hell could break loose in Israel. It is important to understand why.

Prime Minister Benjamin Netanyahu, not without reason, is asking the Palestinians to recognize Israel as the “nation state of the Jewish people,” confirming that if Israel cedes them a state in the West Bank, there will be two-states-for-two-peoples. But, for Netanyahu to get an answer to that question, he will have to give an answer to a question Israelis have been wrestling with, and avoiding, ever since the 1967 war reconnected them with the heartland of ancient Israel, in the West Bank, known to Jews as Judea and Samaria. And that is:

“What is the nation state of the Jewish people?”

Kerry, by steadily making the answer to that question unavoidable, has set the whole Israeli political system into a roiling debate, with some ministers shrilly attacking Kerry and slamming Netanyahu for even putting the question on the table — as if the status quo were sustainable and just hunky-dory.

For instance, Kerry recently observed at a conference in Munich that if the current peace talks failed “there’s an increasing delegitimization campaign that’s been building up [against Israel]. People are very sensitive to it. There are talks of boycotts and other kinds of things.”

Some Israeli ministers and American Jewish leaders blasted Kerry for what they said was his trying to use the B.D.S. movement — “boycotts, divestment and sanctions” — as a club to pressure Israel into making more concessions. I strongly disagree. Kerry and President Obama are trying to build Israelis a secure off-ramp from the highway they’re hurtling down in the West Bank that only ends in some really bad places for Israel and the Jewish people.

I like the way Gidi Grinstein, the founder of the Reut Institute, a nonprofit that works on the thorniest problems of Israeli society, puts it: “We are in a critical moment in our history — far more significant than many realize.” Ever since 1936, “the Zionist movement has sought to establish a sovereign Jewish and democratic majority in Zion, and, therefore, eventually accepted the principle of two-states-for-two-peoples: a Jewish state and an Arab state.” Although there is a powerful settler movement in Israel that would like to absorb the West Bank today, the State of Israel has continued to tell the world and the Jewish people that, under the right security conditions, it would cede control of that occupied territory and its 2.5 million Palestinians and forge a two-state deal.

If Kerry’s mission fails — because either Israelis or Palestinians or both balk — he will either be tacitly or explicitly declaring that this two-state solution is no longer a viable option and “that would plunge Israel into a totally different paradigm,” said Grinstein, who recently authored the book “Flexigidity: The Secret of Jewish Adaptability.”

It would force Israel onto one of three bad paths: either a unilateral withdrawal from parts of the West Bank or annexation and granting the Palestinians there citizenship, making Israel a binational state. Or failing to do either, Israel by default could become some kind of apartheid-like state in permanent control over the 2.5 million Palestinians. There are no other options.

But what these three options have in common, noted Grinstein, is that they would lead to a “massive eruption of the B.D.S. movement” and “the B.D.S. movement at heart is not about Israel’s policies but Israel’s existence: they want to see Israel disappear. What is keeping the B.D.S. movement contained is that we’re still in the paradigm of the two-state solution.” If that paradigm goes, he added, not only will the B.D.S. movement launch with new momentum, but the line between it and those around the world who are truly just critical of Israel’s West Bank occupation will get blurred.

Furthermore, being the “nation state of the Jewish people,” means that the values of Israel cannot be sharply divergent from the values of the Jewish diaspora (the vast majority of American Jews vote liberal) or from the values of America — Israel’s only true ally. Added Grinstein: “If that happens, the relationship between Israel and America and American Jewry will inevitably become polarized.”

To avoid that, no one expects Israel to concede to whatever Palestinians demand or to accept insecure borders or to give Palestinians a free pass on their excesses. And Kerry is not asking that. Israel should bargain hard and protect its interests. “But Israel has to be seen as credibly committed to ending its control over the Palestinians in the West Bank,” concluded Grinstein, otherwise it won’t just have a problem with B.D.S., but eventually with America and a growing segment of American Jews — “turning Israel from a force of unity for Jews to a force of disunity.”

So responding to the Kerry plan, when it comes, is about something very deep: What is the nation state of the Jewish people — and how will Jews abroad and Israel’s closest ally, America, relate to it in the future?