It's the week after the High Holy Days and, once again, Jewish life is returning to normal. So the odds are good that any nearby temple or synagogue will have plenty of empty spaces in its pews and parking lots.

Thousands of American Jews worry about this. Millions do not. Thousands live their lives as if Jewish traditions make a difference in this life or the next. But millions do not.

Thus, the "most divisive factor in American Jewish life is ... Judaism," argues Jewish conservative Elliott Abrams, in his controversial book "Faith or Fear: How Jews Can Survive in a Christian America." Millions of Jews no longer fear God. Instead, they fear people -- even other Jews -- who believe in God. This cannot continue if Judaism is to survive in America.

"A return to Judaism must, inevitably, leave some Jews by the wayside," concludes the former Reagan administration assistant secretary of state. "Those who have lost all religious faith are tied to the community only by brittle bonds of ethnic memory, family history or personal interpretations of Judaism as a social or political force. They are free to entertain their own definitions of Judaism, but the organized Jewish community has no such luxury in the face of demographic disaster."

It's impossible to avoid the statistics. Once, Jews made up nearly 4 percent of the U.S. population. Today the figure is just over 2 percent. A recent American Jewish yearbook found a "core" population of 5.9 million practicing Jews, converts and "secular Jews." While most writers focus on intermarriage trends, Abrams also pays close attention to issues of faith. For example, a 1990 poll found that 1.1 million people of Jewish descent now claim no religion at all and another 1.3 million practice another faith. The researchers said only 484,000 American Jews regularly attend synagogue or temple services.

What to do? Everyone knows Jewish marriages tend to produce Jewish children and that Jewish marriages are more likely to occur among observant Jews, said Abrams. One of the only reliable ways to encourage traditional Jewish faith is to send children to Jewish schools. This will require a strategic change in most Jewish communities.

"If we went from 1 to 2 percent of Jewish children receiving a Jewish education to about 10 percent, even that would be a big change," he said. "Above all, it would be a sign that the community is once again thinking about the future. This also would produce a new generation of Jewish leaders."

But for traditional faith and education to increase, many Jewish leaders will have to face their own prejudices against the Orthodox. Abrams notes that most American Jews would "be more upset to learn that a child of theirs was to marry an Orthodox Jew and become Orthodox than that their child was marrying a non-Jew and was going to lead a secular existence."

In one pivotal 1994 case, mainstream Jewish groups united in opposition to an Orthodox community seeking government support for education of its disabled children. Apparently it is not enough for the state to be neutral on religion. Instead, "any state action whose effect is to help parents keep their children faithful to their religious beliefs" must now be ruled unconstitutional, said Abrams. "The elements of the Jewish community having the greatest difficulty keeping their children Jewish used the courts to attack the practice by which the elements having the greatest success keeping their children Jewish were doing so."

These kinds of debates almost always return to issues of faith. Even Jews who seek unity in ethnicity or social ethics will face eternal questions. Is God real? Does God want Jews to live a certain way? Does the Torah - the scriptural heart of Judaism -- have authority today?

"It's hard to say that the Torah is relevant when it talks about peace and justice, but it's out-of-date when it talks about marriage and family life," said Abrams. "That just doesn't work. It's a pick-and-choose brand of faith. That kind of truth has no transcendence, no power, and it doesn't last from generation to generation. It can't hold people together."