One of the central themes of the book of Ruth is faithfulness, which is displayed through Ruth's faithfulness to Naomi, Boaz's response to Naomi's plight, and God's attitude toward those who suffer.
Naomi and her family are enduring a famine as chapter 1 opens; they are therefore forced to travel to Moab. Soon afterward, her husband dies, leaving Naomi with two sons. Both sons both marry women from Moab: Ruth and Orpah. After living in Moab for ten years, both of Naomi's sons die, and all three women are forced to exist as widows in a society which was not structured to support the financial independence of women.
Naomi releases her daughters-in-law from their obligations to her, instructing them to go back to their mothers and build a new life for themselves. Orpah kisses her goodbye and leaves, but Ruth proves faithful, refusing to leave Naomi. She professes this loyalty with sincerity, and her words are often quoted today as a testament of true devotion:
Don’t urge me to leave you or to turn back from you. Where you go I will go, and where you stay I will stay. Your people will be my people and your God my God. Where you die I will die, and there I will be buried. (1:16–17)
Later Boaz, who is a guardian-redeemer (or a close relative whom extended family can turn to for help), is impressed with Ruth's faithfulness to Naomi. When he sees her attempting to scavenge in his fields, he confronts her—yet not in the way she expects:
Boaz replied, "I’ve been told all about what you have done for your mother-in-law since the death of your husband—how you left your father and mother and your homeland and came to live with a people you did not know before. May the Lord repay you for what you have done. May you be richly rewarded by the Lord, the God of Israel, under whose wings you have come to take refuge."
Ruth finds favor with Boaz, a man of influence, because she demonstrates incredible loyalty. He tells Ruth that she has demonstrated "noble character," which is known throughout the town. Boaz is so impressed by Ruth that she becomes his wife and the mother of Obed, who is the grandfather of David. This is significant because Jesus is a descendant of the line of David.
God therefore demonstrates loyalty to those who love him through this story. Naomi was not left alone even though she lost her husband and both sons. Instead, God gave Naomi the gift of Ruth, a faithful companion and friend. Ruth was not left destitute when she chose to remain faithful to Naomi. It would have been much easier for Ruth to marry again, moving on with a new husband. Instead, she refuses to abandon Naomi, even though there were precious few opportunities for widowed women during this historical context. God was faithful to bless Ruth for her loyalty, making her part of the story of Jesus. Although circumstances may seem hopeless at times, the book of Ruth demonstrates that God can redeem suffering for those who are faithful to his commandments.