'It never even occurred to me that the Jews were a people." I had just finished speaking on Shabbat morning at a traditional shul on Long Island. The talk had been about the nation-state and its roots in the Book of Genesis. Along the way, I'd made some comments about the changing nature of American Jewish life today, and the much-reduced role that peoplehood now plays in American Jews' sense of self. After services, someone told me that members of the liberal synagogue across the street had come to hear the talk. Ouch. I'd been rather direct about the dangers of liberal American Judaism's diminishing the role of peoplehood in Jewish life, and worried that I might have offended the visitors. But it turns out that they were more intrigued than anything else. One woman said that the idea that the Jews were a people had never occurred to her. Another person remarked that peoplehood was an interesting idea, but warned that if Jews are a people, "â€¦ you're going to cut 40% of my congregation out of the picture." Almost without our noticing, American Jewish life is being dramatically redefined. Especially among the young and the liberal, American Judaism is being recreated in the model of American Protestantism. Christianity is not about peoplehood. "The Christian People" is a meaningless phrase. Judaism, like Protestantism, has become a faith system, a purely personal - and highly individual - means of constructing meaning in our world. Judaism as a faith system, of course, is nothing new. But from time immemorial, we have also seen ourselves as a people. From the moment that Pharaoh refers to the Jews as "the people, the Children of Israel" (Exodus 1:9), it is clear even to our enemies that Abraham's clan has morphed into a nation. FOR MILLENNIA, rank-and-file Jews understood this. We cultivated bonds of mutual obligation, even when we profoundly disagreed, even when our faith wore thin. Kol Yisrael areivim zeh la-zeh, all Jews are responsible one for another, the tradition has long insisted. And it actually worked. It was peoplehood that got American college students to wage a relentless battle to free Soviet Jews, with whom they had virtually nothing obvious in common. It was due to peoplehood that IAF pilots flew converted cargo planes into an Ethiopian civil war in order to save people of a different race, a radically different faith system and virtually no shared history, bringing them to Israel in Operation Solomon. And it is peoplehood that has continually led American Jews - despite their absolute disinterest in making aliya and their profound differences with Israel about conversion policy and the peace process - to support Israel both financially and politically. This move away from peoplehood will continue as intermarriage becomes more common. Flourishing marriages, after all, are possible even when spouses disagree about important issues. And therefore, in the logic of young American Jews, there's nothing terribly illogical about my choosing to spend my life with someone who's not Jewish. After all, on a host of issues, I have my opinions and she has hers. So, too, in religious life. I have my synagogue, she has her church. I have my holidays and she has hers. I believe my beliefs, and she has hers. But peoplehood? If I'm a member of a people, then there's actually a yawning chasm between us. And since she has no interest in becoming Jewish, it's Judaism - and not she - that must change. Consciously or not, I sense that Judaism must be redefined - as a faith system, a personal odyssey, as "my Judaism," to use a problematic phrase now popular among American Jews. As anything but a people. YET WITHOUT peoplehood at the core of American Jewish life, devotion to Israel becomes a choice, not an instinct, as it used to be. Young American Jews look with horror at the suffering of Palestinians, and decide that this conflict is simply not theirs. One of the founders of Fast for Gaza (www.fastforgaza.net) wrote recently that "unlike previous generations, [today's young American Jews] don't necessarily understand their Judaism in traditionally tribal terms anymore. â€¦ Rather, they are increasingly viewing their Jewishness against a larger, more universal global reality. In short, to be a Jew and a global citizen is what gives them 'goose bumps.'" This writer himself admits - the new, personal, less "tribal" (i.e., less peoplehood-oriented) Judaism is more animated by global citizenship than by a sense of Jewish responsibility. (That's why they fast for Gazans, and not for Israelis under Gaza rocket fire or for Gilad Schalit, I assume.) From afar, it would seem that there is little that Israel and Israelis can do to influence this seismic shift. But the dangers to Israel's security as a result of this change are obvious. Something must be done. One idea for starters: Recent studies show that a quick trip on Birthright has lasting implications for Jewish identification, and dramatically lowers intermarriage rates, for example. It's because in Israel, Jews encounter peoplehood, with all its problems, but also with its triumphs. It's time to take the Birthright concept and expand it. Two-thirds of Canadian Jews and 75 percent of Australian and French Jews have been to Israel, but about two-thirds of American Jews have never even visited. That has to change. Even in this economy, there is more than enough American Jewish money to get the vast majority of American Jews to Israel, to witness first-hand the power of peoplehood and, perhaps, to transform the dangerous, emerging American Jewish sense that attachment to other Jews and their state is a relic of the past. We know what's at stake. Those people who never even imagined that Jews are a people are the men and women who in a generation will be running the federations, many of America's synagogues and national organizations. They will be setting communal agendas and disbursing American Jews' money. Either they will argue our case on Capitol Hill, or no one will. We would be fools to imagine that we do not need those American Jews at our side. But we'd be equally foolish to believe that they'll care one whit about us, unless we can restore peoplehood to the central value it used to be. The writer is senior vice president of the Shalem Center in Jerusalem. He is the author, most recently, of Saving Israel: How the Jewish People Can Win a War That May Never End (Wiley, 2009). He blogs at http://danielgordis.org.