The Book of Esther
There are many unique aspects to this Biblical book.
Excerpted with permission from The JPS Bible Commentary: Esther published by the Jewish Publication Society.
Megillat Esther, the Book of Esther in the form that we have it in the Hebrew Bible, provides the story of the origin of Purim, the blueprint for its celebration, and the authorization for its observance in perpetuity.
The story itself is implausible as history and, as many scholars now agree, it is better viewed as imaginative storytelling, not unlike others that circulated in the Persian and Hellenistic periods among Jews of the Land of Israel and of the Diaspora. This story seems to have been known in several different versions, or to have gone through a number of different stages in its development, before it was linked with Purim and incorporated into the Bible.
As a Diaspora story--a story about, and presumably for, Jews in the Diaspora during the Persian period--it provides an optimistic picture of Jewish survival and success in a foreign land. In this it resembles other Diaspora stories such as the biblical Book of Daniel (chapters 1-6) and the apocryphal books of Judith and Tobit. But unlike those books, Esther lacks overtly pious characters and does not model a religious lifestyle.
Esther and Mordechai, by Aert de Gelder, 1685
Esther is the most "secular" of the biblical books, making no reference to God's name, to the Temple, to prayer, or to distinctive Jewish practices such as kashrut [keeping kosher]. Yet Esther, of all the biblical books outside of the Torah, is the only one that addresses the origin of a new festival. For this reason, if for no other, Esther should be considered a "religious" book. Its main concern, the very reason for its existence, is to establish Purim as a Jewish holiday for all generations.
Megillat Esther establishes the Jewishness of the holiday by providing a "historical" event of Jewish deliverance to be commemorated and an authorization, through the letter of Mordecai, for the continued commemoration of the event. Just as the more ancient festivals are historicized and their observance is mandated by the Torah, so Purim is historicized and its observance is mandated by the Megillah.
The Book of Esther serves as the authorizing document for Purim, a holiday that is not mentioned in the Torah. But the Megillah's mandate differs from the Torah's in one crucial respect: it is careful not to say that God commanded the observance of Purim. In fact, God is nowhere mentioned in the book and this absence emphasizes the distinction between the Torah and its festivals on the one hand and the Megillah and its festival on the other. The Megillah makes no suggestion that Purim is an ancient festival that had been forgotten or neglected. Purim is clearly a new festival, of recent origin.