A study by the Pew Forum on Religion & Public Life shows that Americans are switching religions more than ever. As many as one of every two adults does not practice the religion in which they were born or raised. Evangelical and nondenominational Protestantism are the big winners. Catholicism and mainline Protestants are the big losers. As an aging religious group, it is time for Jews to take heed of the changes affecting religion in America because they are Americans, too, and no major trend passes them by. Pew refers to the "marketplace" of religions in the United States, and that is exactly right. People shop around for the religious theologies, practices and communities that suit them. Some may try on a number of faiths until they find the one that fits. This is one of the great benefits of the non-establishment clause of the First Amendment, freedom from the government sanctioning any particular religion and allowing many faiths to thrive. The result has been a healthy competition, a country relatively free from the religious strife that plagues so many societies. Competition means that individuals are unshackled by theologies they may not believe or communities of faith that they may find spiritually or otherwise unfulfilling. How wonderful that there are so many choices available and people can find the religious home they seek - or choose nothing at all if that is where they land. At a time when other religious groups are seeking adherents and promoting their religious faiths, Jewish organizations and institutions generally are so afraid of decline and loss that they turn inwards. The result, however, is that these very insular approaches end up ensuring that decline and loss occur. The reason is that Jews, like other Americans, crave free choice. We are more likely to retain more people because they feel they want to be Jews, not because they have to be. The Jewish communal response to this expression of religious freedom is locked somewhere in another time or place - Europe and North Africa in the 1700s, for example. We keep having the same tired discussions about "preventing intermarriage" or "strengthening Jewish identity" or saving the Jews from assimilation with the right kind of, or enough, Jewish education. Again and again we respond with rhetoric, ideas and programs that circle round and round in the same orbit - how do we keep Jews in? Hundreds of years of discrimination, violence and murder take a huge toll. They create a psychology of fear that results in Jewish isolation, a construct of us and them, insiders and outsiders, Jews and enemies. And with unabashed and straight-faced boldness, as if no one else is listening, we ask how do we keep strangers - meaning all non-Jews - out of our families, out of our synagogues. Out. We don't want to be part of the marketplace of religious ideas and practices, thank you, we just want to be left alone to marry each other and keep everybody inside, safe and secure. This of course is an illusion. STILL, WE fantasize that if we inoculate our young people with enough Jewish education, then they will reject the 98 percent of other Americans they might fall in love with or not be attracted to Zen Buddhism. What nonsense. We all have seen the numbers to prove that the head in the sand, return to the ghetto and hope the gentile will go away strategy is not going to work. No number of day schools or summer camps is going to turn back the clock on religious freedom and competition. IT IS TIME for Jews to join every other group in America and quit obsessing about who is being lost and start acting on who might come in. Right now it is largely a one-way street because we cling to dangerously obsolete ideas, attitudes and practices about conversion. We do not welcome people with open arms but rather we stiff-arm. We still question people's sincerity - do they really want to be Jewish? We make people jump through hoops. Those who convert have to be persistent enough to batter down the barriers. Yes, of course we need standards and procedures - and to say that making Judaism more accessible means abandoning rules of admission is a straw argument to cover up how suspicious, off-putting and unfriendly we often are to those who want to be part of the Jewish people. Openness and excitement do not mean that learning and ritual requirements to become a Jew should be abandoned. Just the opposite is the case. Spiritual seekers are looking for meaning, content and purpose. Becoming a Jew can be a deeply intellectual and emotional experience, and spiritual seekers are willing to engage in rigorous education about Jewish life, rituals of conversion and rites of passage to become a Jew. Some rabbis do a great job in dealing with potential converts; many do not. Our synagogues often are less welcoming than we think. And our newspapers, sermons and sociological literature are filled with hysterical reprimands and dire predictions about the demise of the Jews that result from gentiles breaking through our traditional walls. How welcoming do we think it is when we say we wish our sons or daughters would have married someone else, but as long as you are here, we will try and be nice to you? WE HAVE a theology that has no intermediary between the individual and God. That is appealing. We have a set of daily, monthly and yearly rituals that provide guidance and purpose. That is appealing. We have rich liturgy, beautiful prayers, deep roots in Israel, a strong communal system. All appealing. By being attractive to others, we will also be more attractive to born Jews. What are we afraid of? We are checkmated by our own notion of ourselves that Jews don't do that - we don't compete for newcomers. Maybe Jews in 18th century Poland did not - and with good reason. It brought the wrath of the church and the state on them. But this is 21st century America, not 18th century Poland or 20th century Germany. Pew tells us that Americans are switching religions like never before. Do we want to enter the competition armed with our wonderful 3,000-year-old history, or kvetch about assimilation, intermarriage and our dwindling numbers? Those who choose to join the Jewish people will enrich us with their ideas, energy and passion. And born Jews who choose to embrace their Judaism in an open marketplace also will enrich Jewish life. It is time to embrace the America in which we live. We must abandon the paradigm that our children and grandchildren are potential gentiles and promote the new belief that America is filled with potential Jews. The writer is the president of the Institute for Jewish & Community Research in San Francisco and writes frequently about American and Jewish philanthropy.