(Excerpted from Rabbi Ginsburgh’s book, “The Art of Education”)
Both Abraham and Sarah are the spiritual parents of every convert to Judaism, whether male or female. Nonetheless, in the Torah, Abraham alone is called “the father of many nations [ie., converts], as it is particularly his propensity for inspirational enlightenment that draws potential converts to identify with the Chosen People. Sarah, on the other hand, is depicted in the Talmud as figuratively “inspecting and cleaning the hair of Abraham’s head,” that is, removing those converts whom she does not deem fit to dwell with her children (just like she vanquished Hagar and her son Ishmael). As such, Sarah clearly identifies more with her and Abraham’s physical offspring.
This relative difference (and complement) between Abraham and Sarah may also explain the difference between a male and female convert from the Biblical nations of Moab and Ammon. Whereas the female convert can marry freely within the Jewish people, the male convert cannot. The male’s conversion is considered relatively “spiritual,” limiting him with regard to his physical connections, while the female, who naturally identifies more with Sarah, undergoes a relatively more “physical” conversion, thus permitting her to unite in marriage with another Jew.
Thus, we may say that while a convert to Judaism is the spiritual child of Abraham, inspired, like Abraham, by his higher spiritual truth, a person who is Jewish by virtue of his or her mother’s Jewishness is a spiritual child of Sarah – Abraham’s wife and our first matriarch, through whom the integration of Abraham’s beliefs were actually passed on. Thus, Abraham and his wife Sarah represent the ideal integration. Indeed, in the Zohar, they are referred to metaphorically as “soul” and “body,” respectively. Moreover, Kabbalah teaches that the souls of converts, in their generation and in all generations to come, arose from the marital unions between Abraham and Sarah that did not actually generate natural children of flesh and blood. This is alluded to in their names, for Abraham means “father of many nations” and Sarah means “officer of all.”
 Genesis 17:5.
 Bava Batra 58a. For an in-depth explanation of this passage in the Talmud, see Tzemach Tzedek’s Or Hatorah, Chayei Sarah (folio 119b) “Rabbi Bena’ah.”
 See Genesis 21:10.
 Deuteronomy 23:4.
 Shulchan Aruch, Even Ha’ezer 4:2.
 This manner of corresponding Sarah with the more physical conversion of women and Abraham with the more spiritual conversion of men “sweetens” the proto-Chassidic interpretation offered in Shut Harashba (part 1), 418.
 Berachot 13a.