In Judaism, there are four main branches. Reform, Reconstructionism, Conservative and Orthodox. Of those, Reform and Reconstructionism will accept "patralineal descent" - meaning if your father is Jewish, but your mother is not, then you are Jewish. However, Conservative and Orthodox groups have followed the original tradition of only accepting "matrilineal descent" - meaning that your mother must be Jewish, and will not accept those of patralineal descent as Jews unless they convert. (If one is a convert, then this is a moot point. If one is adopted, conversion is necessary if one would not be considered Jewish because of the birth parent's religion according to the group of Judaism one is affiliated with.)

The reality is that many, many Jews are in interfaith relationships. This is an excerpt of an interesting article that appeared in today's Star Ledger regarding a new direction being taken by some in the Conservative movement.

For decades, Jews marrying outside the faith have been sermon fodder for Conservative rabbis, who have lambasted intermarriage as the bane of the American Jewish existence.

The rabbis have feared that with intermarriage rates nearing 50 percent -- and, more critically, with only a third of intermarried couples raising their children to be Jewish -- the American Jewish population, estimated at 5.2 million, will dwindle to insignificance in a few generations

But that attitude toward intermarriage has come with a price that increasing numbers of Conservative rabbis in New Jersey are acknowledging: the alienation of intermarried couples from Judaism, at least from its Conservative movement.

Now, a document circulating through Conservative temples, the religious middle ground for American Jewry, is calling for a warmer embrace of interfaith couples, both to encourage conversions and to improve the odds the couples will raise Jewish children.

The document does not propose changing the Conservative ban on synagogue membership for non-Jewish spouses. But it encourages better treatment for them at services and in synagogue communities -- suggesting, among other things, that temples stop excluding the name of the non-Jewish spouse from mailings to the home.

Rabbis of six Conservative temples in Essex and Union counties have openly embraced the document, sharing the concern that existing attitudes have estranged too many interfaith couples from Conservative shuls and hurt the cause of "Jewish continuity."

"We have to some rethinking so we don't lose these families, and so we don't lose the children of these families," Rabbi Moshe Edelman, who wrote the document, titled "On the Path," said at the first event, held March 22 at Temple Beth Ahm.

"It's a change in attitude we're looking for -- to say, 'We have people (interfaith couples) in our congregation, men and women who have fallen in love. They are married. And that reality is there.'"

There is no simple path, said Jonathan Sarna, a Jewish studies professor at Brandeis University and author of "American Judaism."

Giving non-Jews too many rights can reduce the incentive to convert, while strictly observing rules can alienate, he said. Middle ground can be hard to find.

"It's not that easy," he said. "The Reform movement, too, is deeply worried that, having made it so good for non-Jews belonging to the congregation, they now have congregations that are filled with unconverted non-Jews. And that poses enormous challenges to a Jewish temple or synagogue."