Who is a Jew? This question is endlessly debated, and has become the source of controversy in the Knesset as well as in rabbinical circles. There is another related question, however, that should command our attention and seldom does, and that is: What is a Jew? What are the qualities and characteristics that, according to the tradition, make us what we are or what we should be? There are many sources that deal with this, all of which have a common answer: A Jew is one who follows the ways of goodness and decency in human relationships. Let us look at three formulations of this basic truth. One such formulation is given in Pirkei Avot, a general guide to Jewish living and the only section of the Mishnah that deals with questions of belief and theology: Whoever possesses these three qualities is a disciple of our father Abraham: a generous spirit, a humble soul, a modest appetite [not greedy]. Whoever possesses these three qualities is a disciple of the wicked Balaam: a grudging spirit, an arrogant soul, an insatiable appetite. (Avot 5:21) These specific qualities were derived from verses in the Torah describing the lives of these two men. The important thing is the qualities that the Sages identified with the father of our people and wanted to inculcate in us as the proper way to live. Note that they use the phrase "disciples of" rather than "children of," to indicate that biological descent is not critical. It is more important to be a disciple of Abraham, to live according to his ways and his teachings, than to be a biological descendant of him. One who takes pride in being a Jew should consider that conduct is more important than birth. One can be a Jew by accident of birth, but one is worthy of being a disciple of Abraham only if one shares Abraham's qualities. Modesty, humility and generosity are the marks of the true Jew. A second source teaching us the qualities that define a Jew is found in the words of the prophet Jeremiah: "Let not the wise man glory in his wisdom; Let not the strong man glory in his strength; Let not the rich man glory in his riches. But only in this should one glory: In his earnest devotion to Me. For I the Lord act with kindness, justice and equity in the world; for in these I delight." (Jer. 9:22) A Jew is defined as one who acts with kindness toward others and promotes justice and equity among human beings. Wisdom, physical strength and wealth are not the ultimate goals of life, rather they must be used to achieve social justice in the society in which we live. Jeremiah has a unique definition of devotion to God, of closeness to the Almighty. It is not to be found in piety, not in worship or sacrifice, not even in observance of rituals, important as these may be. The first measure of devotion is in one's conduct toward others, a mixture of kindness and justice. In a world filled with corruption, favoritism and inequality, the Jew is one who works to eliminate these injustices and establish instead a society that will bring delight to God. Finally there is the answer given by Hillel to the potential proselyte, who asked to be taught the whole Torah standing on one foot. "That which is hateful to you, do not do to your fellow human being," replied Hillel, "that is the whole Torah. Go study," (Shabbat 31a) giving a negative Aramaic formula of the verse "Love your fellow as yourself" (Leviticus 19:18). The same answer was given a hundred plus years later by Akiva, who called that verse "A great general rule of the Torah" (Y. Nedarim 9:4). Obviously neither Hillel nor Akiva were contemptuous of all the other commandments in the Torah, nor did they wish to eliminate rituals. What they were saying was that the goal of all the observances in the Torah is the creation of a human being who will act lovingly toward all others. If that is not achieved, the observances have not attained their goals. What, then, is a Jew - a true Jew, an ideal Jew from the view of the tradition itself? A person of humility and generosity, devoted to the creation of an equitable, just society built on kindness; one who in all his or her dealings demonstrates love toward others. Yes, there are formal rules that govern the question of one's Jewishness, but far more important are the teachings that define for us what it means to be a Jew - a true disciple of Abraham, of the prophets, of Hillel and Akiva. That should be the content of our teachings and the way in which we measure Jewishness. It is the goal of Jewish living, a goal that is far from being achieved but worthy of our best endeavors. The writer is the head of the Rabbinical Court of the Masorti Movement and the Rabbinical Assembly of Israel.