Here is a conclusion from a Pew study conducted in 2007, released in 2008, and revised in 2011: “Americans change religious affiliation early and often. In total, about half of American adults have changed religious affiliation at least once during their lives.” Religious switching is part of the enormous freedom of American life. We like to choose our music and our clothing. And, increasingly, we don’t consider our birth religion as final. We also like to choose our religion. Most of the religious switching that occurs is between one Protestant denomination and another, but each year thousands of Americans who were not born Jewish join the Jewish people. We don’t know the exact number because no official record is kept of conversions to Judaism, no central authority is responsible for keeping track of how many occur or who exactly is becoming Jewish.

There are, naturally, many reasons why people convert to Judaism. In the show Seinfeld, Jerry'sdentist became Jewish, but Jerry accused him of doing so only for the jokes. Perhaps the reputation the Jews have as funny people is justified, but there are other, more substantive reasons, why American Gentiles become American Jews.

There are, broadly speaking, four types of reasons why people become Jewish: spiritual, romantic, communal, and personal.

Many people, for example, examine Judaism as part of a wider spiritual search. Perhaps a specific event such as an illness, or the death of a loved one, or a painful divorce, or a breakup prompted a spiritual crisis that resulted in the need to form a new spiritual self-definition. After examining their options, some people conclude that the Jewish worldview, set of values, and set of ethics provide them with the sort of spiritual compass they need to get them traveling along the spiritual path that is right for them. Some people see in Judaism very familiar spiritual ground that they are familiar with from reading the Hebrew Bible in their Sunday School classes, or they have gone in search of the Jewish roots of Christianity. Perhaps they find religious services attractive. Perhaps, for example, they have attending a Bar or Bat Mitzvah, or a Sabbath dinner, or a Passover Seder.

It should be noted, though, that Judaism does not intend that any conversion be done out of fear, emotional pressure, bribery of any type, or religious coercion. Judaism specifically doesn’t see itself as the only route to salvation. The righteous among all people, Judaism says, have a share in the world to come. Indeed, many potential converts are encouraged first to study their birth religion before embarking on the course of study that leads to conversion.

Many people, the large majority of whom are women, are introduced to Judaism because they fall in love with a Jewish partner. This relationship leads to family concerns. Some want to ensure that their children are raised in a unified religious household, one that promotes family harmony. Some find that the person they love is already deeply Jewish, or that he or she discovers a deep-seated attachment to a Jewish identity, and that partner wants their love to share that identity.

There are also communal reasons for conversion to Judaism. Many who convert admire the way Judaism encourages questioning. In the Bible, Abraham and Moses are shown arguing with God. The Talmud, a central Jewish religious text, begins with a question. There have even been times in Jewish history in which rabbis or ordinary Jews put God on trial for allowing Jewish suffering. For example, a prominent Hasidic master named Rabbi Levi Yitzhak of Berditchev by tradition challenged God on one Rosh Hashanah to a lawsuit. After all, Rabbi Levi argued, God had no right to prolong Israel’s exile from the Promised Land, when other nations, including some cruel and violent ones, still were permitted to reside in peace in their native lands. In his incredible memoir Night, the Nobel Laureate Elie Wiesel recounts how some inmates in Auschwitz held a trial to condemn God for allowing the evil and human suffering that they saw on a daily basis. Wiesel later wrote a play, though not one set in the Holocaust, titled The Trial of God.

Many people admire the fierce family closeness that characterizes Judaism, or the love of lifelong learning, or the unique history of the Jewish people, who, for four thousand years, have been everywhere, done all that good be done, reached the spiritual heights, suffered deadly persecution, and lived to tell about it all. The Jews, after all, two thousand years after the loss of their homeland summoned the will to rebuild that homeland and reclaim Hebrew, their ancient, sacred language. The Jewish story is invariably fascinating, and some potential converts love to hear it.

And, finally, there are a myriad of personal reasons why people become Jewish. They were, perhaps, looking for a new life, or were excited by the possibility of embarking on a religious path strange to them. Judaism, after all, is unfamiliar to many people with its religious language, its books, its rituals and rites, and its customs.

It is not always obvious why people become Jewish; sometimes it is not obvious even to themselves. More than one person, for example, has decided to explore Judaism and when they began that exploration they discovered that they had Jewish ancestors. Many millions of people do without realizing it. One woman told me that she felt she had been born into the wrong Earthly religion, that her becoming Jewish was a way to correct a cosmic error.

Whatever the reasons why people become Jewish, they are certainly needed. The Jewish people remains a numerically small minority, in need of new members to provide new ideas and new energy. The Jewish community, for many reasons, only recently has re-discovered its ancient history of welcoming converts, a history as long vanished as the Jewish nation that re-established itself. It’s an interesting phenomenon to observe Judaism discovering its legitimate but often forgotten heritage of welcoming converts and the converts themselves who, with some courage, have decided to cast their fate with the Jewish people and join that people on its historic spiritual journey.