Question: "Why isn't God mentioned more in the book of Ruth?"
Answer: The book of Ruth mentions God several times, but it does not record God directly speaking or doing anything out of the ordinary—if we can call the birth of a baby “ordinary.” There are no miracles recorded in the book of Ruth, no dreams or visions, and no exposition of divine lessons or relaying of commands. There are not even any prayers in the book.
When God is mentioned in the book of Ruth, He is always referred to by His covenant name, Yahweh. The book of Ruth mentions the Lord as the One who “blessed his people in Judah by giving them good crops again” (Ruth 1:6, NLT). Various people in the book invoke God’s name in oaths (verse 17; 3:13) and some formulaic blessings (Ruth 1:8, 9; 2:4, 12, 20; 3:10; 4:11, 12). Naomi, Ruth’s mother-in-law, blames God for bringing her to a state of misery (Ruth 1:13, 21). At the end of the book, the author mentions that it is the Lord who enabled Ruth and Boaz to have a son (Ruth 4:13), and the women of Bethlehem utter a note of praise: “Blessed be the LORD” (verse 14, ESV).
With its relatively few references to God, the book of Ruth somewhat resembles the book of Esther. In Esther, God is never mentioned at all. But, in both Esther and Ruth, God’s hand can be seen moving and working “behind the scenes.” For example, the famine in Israel, mentioned in Ruth 1:1, was a divine judgment of idolatry in the land (Deuteronomy 11:16–17).
Also, like Esther, Ruth contains an amazing “coincidence” that points to God’s covert design. Ruth 2:3 records, “So [Ruth] went out, entered a field and began to glean behind the harvesters. As it turned out, she was working in a field belonging to Boaz, who was from the clan of Elimelek.” Out of all the fields in the Bethlehem region, Ruth “happened” to end up in Boaz’s field, and Boaz just “happened” to be an eligible kinsman-redeemer for her. The text makes it sound as if Ruth’s arrival in the field was a random event, a happy accident. But we know that Ruth’s meeting Boaz was more than happenstance. The last word in the book of Ruth—David (Ruth 4:22)—reveals what God had been doing all along: bringing into the world a king who would be a man after His own heart. God sovereignly led the widow Ruth to the field of the one man both willing and able to redeem her according to the law.
Although He is not mentioned often in Ruth, God orchestrated all the events recorded in the book. He provided an honorable kinsman-redeemer for both Naomi and Ruth in the person of Boaz. He arranged for a Moabite widow to be welcomed into Judean society. Under His direction, all the pieces fell into place for the birth of David, the future king. While the book of Ruth does not explicitly record God causing all these things to occur, the reaction of the women of Bethlehem makes it clear that they knew it was the LORD’s doing: “Praise be to the Lord,” they say, “who this day has not left [Naomi] without a guardian-redeemer” (Ruth 4:14).