Five thousand years ago, a tiny band of nomads made what was then a fantastic claim: that God is one. Uncompromising monotheism remains the central characteristic of Judaism, leading the way for Christianity and Islam. During every morning and evening worship service Jews fervently repeat the Shema - ''Here, O Israel, the Lord our God, the Lord is One.'' From the Shema stems Judaism's answers to the other basic questions of existence:
* What does this God encompass? Genesis tells us: ''In the beginning, God created the heaven and the earth,'' building to the climax, ''and, behold, it was very good.'' Unlike pagan nature gods, which were often deemed amoral, Jews see this one God as all powerful, full of goodness, and concerned with history.
* What is the meaning of God's creation? It represents His goodness - ''behold, it was very good.'' Whereas the Greeks and later, the Christians, placed the transcendent above the material, Jews tend to scorn asceticism and rejoice in material life as part of God's great gift.
* What is man? Compared to God, the Psalms say he is ''merely dust.'' In the Jewish view, man is a sinner; yet he is also God's beloved child - according to one Psalm, ''a little lower than the angels'' (''... than divine,'' in the original Hebrew). He is free to choose between good and bad, just as Jews believe Adam chose. The orthodox Christian concept of original sin is rejected.
* What is God's relationship to His child? Amid man's tendency to err, He intervenes. He calls Abraham, who goes forth into a new land to establish a ''chosen'' people. God is directly concerned with how life is lived in this world, and He teaches the faithful through history. He delivers them from Egyptian bondage and punishes them with exile.
* What is man's responsibility to God? To be moral. If God is Himself good, there can be little question about His will for man. He must be good. Thus, on Sinai, the Jews were given the law, the Ten Commandments, the minimum standard to which they are held.
* What is man's responsibility to man? To be just. Not only does God demand in the Ten Commandments a minimum of respect, He also demands through His prophets that man show concern for his fellow man. In the first century, the famous Rabbi Akiba pointed to the verse from Leviticus in the Torah, ''Thou shalt love thy neighbor as thyself,'' as summing up Judaism's entire lesson.
These ideas form the basis of the Jewish outlook, but in many ways they do not explain Jewish belief. Judaism stresses action, not theology. The basic manual of the faith is actually called the Law (the meaning of the Hebrew word ''Torah''). It is expanded on in the post-biblical Talmud and the Midrashim, vast compendiums of law, commentary, and history.
Observance and ritual are everywhere. Jews believe that all life down to its smallest element can, if rightly approached, be made holy. Hundreds of rituals regulate a Jew's daily existence.
Jewish holidays are also filled with traditional symbols: the Sabbath, with its candles and cup of wine; Passover, with its matzo (thin unleavened bread); the sounding of the ram's horn on the new year. To the Jew, all these express the meaning of life, a meaning that has spanned the centuries, ever since that tiny band of nomads dared to make their fantastic claim.
SOME DEFINITIONS OF TERMS USED IN THIS SERIES
Bar mitzvah: ceremony for a Jewish boy (or bat mitzvah for a girl) who has arrived at the age of religious responsibility, 13 years.
Diaspora: in general, any scattering of people with a common origin, background, or beliefs. For Jews, the world Jewish community outside of Israel.
Holocaust: the murder of millions of Jews by the Nazis before and during World War II.
Kosher: the designation for food prepared according to Jewish dietary laws.
Mitzvot: commandments or religious obligations.
Passover: a Jewish holiday commemorating the deliverance of the ancient Hebrews from the Egyptians.
Sabbath: the day of the week set aside by the Fourth Commandment for rest and worship. The Jewish Sabbath begins at sundown on Friday and ends at sundown on Saturday.
Synagogue: a place of assembly for Jews to worship and study. In modern usage , the word ''temple'' is synonymous with synagogue. The ''Temple'' refers to the ancient Temple of Jerusalem, of which the Western (or ''Wailing'') Wall is the only remnant.
Talmud: writings that comprise the Jewish oral tradition of law and commentary, illuminating the Torah.
Torah: the first five books of Jewish scripture (the books of Moses) which are the first five books of what Christians call the Old Testament.
Zionism: a movement formerly for establishing, now for supporting, the Jewish national state of Israel.
Zohar: a mystical commentary on the Torah.