In the US, it's socially impolite to ask about an individual's religion. Employers are not permitted to inquire, and the US Census has not sought data on religion for 50 years. So when the Pew Forum on Religion & Public Life, a prestigious American think tank, recently released its US Religious Landscape Survey, it performed quite a service. The survey of 35,000 adults is the most important snapshot of religious demographics in America, and it offers many tidbits we were afraid or barred from asking. It does not discuss religious beliefs and practices, but it says much about the faithful. "Faithful" may be too strong a word. Maybe the issue is fidelity. Or lack thereof. According to the Pew poll, a substantial number of people have changed their religious affiliation since childhood. No religious group is standing still, so to speak. Instead, there is constant motion, as every major religious group gains and loses adherents. "People will be surprised by the amount of movement by Americans from one religious group to another - or to no religion at all," said Luis Lugo, director of the Pew Forum. In the nonpartisan Pew poll, religion almost seems to be a commodity. Americans "not only change jobs, change where they live, and change spouses, but they change religions too," Lugo said. The Pew report puts a positive spin on this, referring to the "remarkable dynamism taking place in the US religious marketplace." How depressing. What appears to be dynamic is the ease of shedding one set of beliefs for a new one. It seems to treat faith as the latest fad. Imagine religion as mere merchandise hawked by different faith communities based on a combination of factors, such as convenience and the conviviality of your cohorts. A WORD TO the wary: Jews should not be too excited about the survey by the Pew, which is funded by The Pew Charitable Trusts. The actual number of Jews questioned is small, a fact about which I do not quibble given the small proportion of the Jews in American society. The problem with the Pew poll is that it doesn't tell us much that we don't already know about ourselves. There is nothing about the nature of religious life. Instead, the report reviews the relationship between religious affiliation and demographic factors, including age, family composition, regional distribution and educational and income levels. It is that last factor that often grabs people's attention and is the most irritating. Haaretz led its early report about the Pew poll by saying: "American Jews are the country's highest earning religious group, according to a research study released this week, with 46 percent of Jewish respondents reporting annual incomes of $100,000 or more." If this is the most newsworthy facet of American Jewish life, it is a sad commentary indeed. Jews, who comprise 1.7% of the adult American population, may be the wealthiest religious group in the US, but the Hindus are catching up quickly. And Jews can no longer claim to be the most highly educated. Some 35% of Jews have post-graduate degrees, compared to 48% of the Hindus. Jews still do well in the aging contest, with 22% of the population older than 65. OVERALL, according to Pew, the main gainer in the religious competition is the unaffiliated group, which includes the atheists and agnostics. On the other hand, quite a few adults who say they were not affiliated with any religion as children have come to identify with a religion. But the idea of affiliation should be taken with a grain of salt. The poll relied on the respondents to define their religious identity. Catholics, for instance, are defined as those who call themselves Catholics, whether or not they attend mass. No doubt there are those who are self-identified as Jews, whose last Jewish experience was ordering bagels and lox at Zabars and watching a Seinfeld rerun. The survey found that more than a quarter of American adults left the faith of their childhood in favor of another religion - or for no religion at all. For the record, this was not the case with the Jews, Hindus and Mormons, who have the highest "retention" rate. But this says nothing about commitment to religion. Virtually any Reform or Conservative rabbi in the US can speak about the episodic and cyclical affiliation of Jews, in which parents join synagogues for their children's bar and bat mitzva training. A family might return when it is time for that child to marry, and when the married child has children of his or her own. And, it goes without saying that many a rabbi meets a Jewish family only at funerals, leaving the clergy in the embarrassing and awkward position of trying to craft a meaningful eulogy for someone he has never met and whose heirs he may never see again. SURVEYS provide endless fodder for Jewish academics, pundits, columnists and overeager communal planners who are looking for that magical key to unlock Jewish communal engagement. The decennial National Jewish Population Survey (NJPS) can usually be relied on for a decade's worth of acrimonious debate and hand-wringing about whether the intermarriage rate is as high, as dire, as accurate as the statisticians would have us believe. By the way, the Pew survey found that among the married, some 37% have a spouse with a different affiliation, such as Baptists who are married to Methodists. Perhaps those kinds of intermarriages don't sound the death knell of a faith - they may share certain key rituals and holidays - but it should be clear that intermarriage is not exclusively a Jewish phenomenon. Polls can be enormously useful for communal planning, or degenerate into battles that deflect time and energy from substantive issues. I await the new one from the Pew, which is expected to look at Americans' religious beliefs and practices as well as their social and political views. No doubt Pew's view of Jewish belief and practice will not please the rabbis - of any flavor.