On the holiday of Shavuot, which begins this year on May 24, many Jews follow the ancient custom of reading the book of Ruth in the synagogue. The connection between this book and the holiday is not obvious; Shavuot celebrates the giving of the Torah, while Ruth is the story of a Moabite convert to Judaism who is the ancestress of King David. Micah Goodman argues that the book was chosen to make a point about the connection between the universal and the particular:
Israel is God’s kingdom of priests who live on a higher level of sanctity. But there is nothing in the book of Exodus, [in which the Israelites take on this status and received the Torah], about a universal mission of spreading Torah to the other nations, even though in Genesis God declares that Abraham is to be blessing to all the nations. . . .
Ruth is a foreigner, a daughter of Moab, who is the offspring of an illicit relationship between Lot and his daughter (Genesis 19). Moabites are explicitly excluded from entering God’s community for ten generations. Ruth [thus] has a bad lineage. Yet Ruth will become the model for conversion to Judaism, for the voluntary acceptance of God’s laws, and for joining with God’s people and receiving an inheritance of God’s land. Her lineage will be wiped away, and she will be judged not by her fathers, but by her sons. The genealogy found in the book of Ruth [cataloguing her descendants through David] thus comes at the end of the book, rather than at the beginning as do the genealogies in the biblical stories about Esther and Saul.
Read more on Hartman Institute: http://hartman.org.il/Blogs_View.asp?Article_Id=1532&Cat_Id=275&Cat_Type=Blogs