Many people have asked why traditional Judaism uses matrilineal descent to determine Jewish status, when in all other things (tribal affiliation, priestly status, royalty, etc.) patrilineal descent is used. The Torah does not specifically state anywhere that matrilineal descent should be used; however, there are several passages in the Torah where it is understood that the child of a Jewish woman and a non-Jewish man is a Jew, and several other passages where it is understood that the child of a non-Jewish woman and a Jewish man is not a Jew. In Deuteronomy 7:1-5, in expressing the prohibition against intermarriage, G-d says "he [ie, the non-Jewish male spouse] will cause your child to turn away from Me and they will worship the gods of others." No such concern is expressed about the child of a non-Jewish female spouse. From this, we infer that the child of a non-Jewish male spouse is Jewish (and can therefore be turned away from Judaism), but the child of a non-Jewish female spouse is not Jewish (and therefore turning away is not an issue). Leviticus 24:10 speaks of the son of an Israelite woman and an Egyptian man as being "among the community of Israel" (i.e., a Jew). On the other hand, in Ezra 10:2-3, the Jews returning to Israel vowed to put aside their non-Jewish wives and the children born to those wives. They could not have put aside those children if those children were Jews. Several people have asked how King David could be a Jew given that one of his female ancestors, Ruth, was not a Jew. This conclusion is based on two faulty premises: first of all, Ruth was a Jew, and even if she wasn't, that would not affect David's status as a Jew. Ruth converted to Judaism before marrying Boaz and bearing Obed. See Ruth 1:16, where Ruth states her intention to convert. After Ruth converted, she was a Jew, and all of her children born after the conversion were Jewish as well. But even if Ruth were not Jewish at the time Obed was born, that would not affect King David's status as a Jew, because Ruth is an ancestor of David's father, not of David's mother, and David's Jewish status is determined by his mother.