Lawrence Boadt provides this excellent introduction to the book of Ruth:
The Book of Ruth appears in our Bibles right after the Book of Judges because its heroine is an ancestor of King David, whose story is told in the following Books of 1 and 2 Samuel. It tells of an Israelite woman, Naomi, who marries a Moabite man and goes to live in his country. They have two sons who marry local Moabite women. But soon Naomi loses her husband and both sons in death, and she decides to return home to Israel. One daughter-in-law, Ruth, although a Moabitess, decides to follow Naomi and serve her needs, even though she would be far from her own people. In this way Ruth gives a charming example of filial respect and care that eventually leads to her fortunate marriage with Boaz, the leading citizen of Naomi’s hometown of Bethlehem. From their marriage will come the house of David.
The one thing that is certain about this book is that the story comes from a time long after the period of the judges. Like many children’s fairy tales, it begins, “Once upon a time when there were judges…” It also has great interest in tracing the roots of David and ends with a little genealogy that goes from Boaz to David.
While the story is probably based on an old tale preserved in the folklore about King David and his family which goes back to the ninth or tenth century, it is written in its present form in the post-exilic period, although a more exact date cannot be decided upon. The conflicts with the foreign wives may reflect the struggles over marriage in the days of Ezra and Nehemiah. And like the Book of Jonah, it has an outlook definitely favorable to foreigners. It prefers the pious person, no matter whether Jew or Gentile!
Ruth is a short story of very fine style. The characters all bear symbolic names that almost make it an allegory. Ruth means “companion,” Boaz means “strength,” and Orpah, the daughter-in-law who did not follow Naomi, means “disloyal.” The book has a simple message about true faith in Yahweh. It is not blood or marriage that most matters, but faith. Ruth, although a Moabitess, is a perfect example of Israelite faithfulness at its best.
Boadt's comment is an interesting one. If Ruth was written during the post-exilic period when Ezra was urging the Israelites to get rid of their foreign wives, then this book was written to give an alternative perspective on such wives. Once again we see that the Bible, in a sense, is one book with many voices.
C. S. Lewis has this insightful comment about reading the book of Ruth:
To me the curious thing is that neither in my own Bible-reading nor in my religious life as a whole does the question in fact even assume that importance which it always gets in theological controversy. The difference between reading the story of Ruth and that of Antigone—both first class as literature—is to me unmistakable and even overwhelming. But the question “Is Ruth historical?” (I’ve no reason to suppose it is not) doesn’t really seem to arise till afterwards. It wd. still act on me as the Word of God if it weren’t, so far as I can see. All Holy Scripture is written for our learning. But learning of what? I should have thought the value of some things (e.g., the Resurrection) depended on whether they really happened: but the value of others (e.g., the fate of Lot’s wife) hardly at all. And the ones whose historicity matters are, as God’s will, those where it is plain.
What struck me most in this reading of the book of Ruth was that it felt like waking up to a bright sunny morning after the nightmare of the book of Judges. Certainly, that is part of the message of Ruth, that even in the midst of evil times, there is much goodness to be seen in the world.