Commentary - Deuteronomy 21:15-17

Bird's-eye view

In this brief but potent section of the law, the Lord addresses a messy domestic situation in order to uphold His righteous standards against the sinful tendency of men to play favorites. The law here regulates a polygamous household, not to bless the polygamy, but to bring order and justice into a situation that is already disordered by sin. God is a God of justice, and His law intrudes into the fallen world to protect the vulnerable and restrain the selfish whims of sinful men. The central issue is the right of the firstborn, a right established by God and not subject to the emotional preferences of the father. This law ensures that the objective fact of birth order, and the privileges assigned to it by God, cannot be overturned by a husband's subjective affections for one wife over another. It is a powerful affirmation that God's law stands over and above our feelings.

At its heart, this passage is about recognizing and honoring a God-given reality. The father's duty is not to legislate his own reality based on his affections, but to recognize the son who is, in fact, the firstborn. This points us to a much larger theological reality. God recognizes His only begotten Son, Jesus Christ, as the true firstborn over all creation. Our salvation depends entirely on God recognizing Christ's status and work, not on our fluctuating affections or merits. This law, in its own way, is a shadow of that great reality, teaching Israel that justice, inheritance, and blessing are all grounded in objective realities established by God, not in the fickle hearts of men.

Outline

Context In Deuteronomy

This law comes in a section of Deuteronomy where Moses is applying the general principles of God's covenant to specific situations in the life of Israel. These are not abstract legal codes; they are case laws designed to teach the people how to live righteously in the land God is giving them. This particular law follows instructions concerning unsolved murders and marriage to a captive woman, and precedes the law concerning a rebellious son. The common thread is the application of God's justice and wisdom to the nitty-gritty, often difficult, realities of family and community life. The law is intensely practical. It anticipates the sins and follies of the people and provides a righteous framework for dealing with them. This is not God setting up an ideal society from scratch; it is God graciously giving law to a redeemed but still sinful people to curb their worst impulses and to point them toward justice.

Key Issues

Verse by Verse Commentary

v. 15 “If a man has two wives, the one loved and the other unloved, and both the loved and the unloved have borne him sons, if the firstborn son belongs to the unloved,”

The law begins by stating a scenario. Notice that the law does not command a man to have two wives. It says, "If a man has two wives." This is what we call case law. It is dealing with a situation that will arise in a fallen world. God's original design, laid out in Genesis, was one man for one woman. But sin complicates everything, and polygamy was a common cultural reality, as we see in the lives of the patriarchs. The law here does not endorse the practice, but rather regulates it to mitigate the damage. It steps into the mess to enforce a measure of justice.

The text is brutally honest about the human heart. There is one wife who is "loved" and another who is "unloved" or, perhaps better, "hated." This is the language of preference. We are immediately reminded of Jacob, Leah, and Rachel. Jacob loved Rachel, but Leah was the one who was more fruitful initially. This kind of domestic strife, jealousy, and favoritism is the inevitable fruit of polygamy. The law anticipates this very problem. And the problem comes to a head when the firstborn, the heir, comes from the unloved wife. This sets up a direct conflict between the father's feelings and God's established order.

v. 16 “then it shall be in the day he wills what he has to his sons, he cannot make the son of the loved the firstborn before the son of the unloved, who is the firstborn.”

Here is the prohibition. The father, when it comes time to draw up his will and distribute his inheritance, is forbidden from letting his affections dictate the outcome. He "cannot" do this. The Hebrew is emphatic. He is not permitted to treat the son of his favorite wife as the firstborn if he is not, in fact, the firstborn. This is a direct check on the father's authority. In his household, he is the head, but he is a head under God. His authority is not absolute, and he may not use it to subvert the law of God.

The temptation would be immense. The entire household would know who the favored wife and son were. The pressure to formalize that favoritism in the inheritance would be great. But God's law says no. You cannot redefine reality to suit your emotional preferences. The son of the unloved wife "is the firstborn." It is a statement of fact, and that fact must govern the proceedings. This is a crucial principle for our own day, where people believe they can redefine fundamental realities, like marriage and gender, based on their feelings. God's law is always grounded in objective reality, in the world as He made it and orders it.

v. 17 “But he shall recognize the firstborn, the son of the unloved, by giving him a double portion of all that he has, for he is the first of his vigor; the legal judgment for the firstborn belongs to him.”

The negative prohibition of verse 16 is now followed by a positive command. The father "shall recognize" the firstborn. The word means to acknowledge, to treat as what he is. This is an act of public, legal recognition. And this recognition is not just a title; it has teeth. It means giving him a "double portion of all that he has." The firstborn son was to receive twice the share of any other son. This was not simply a privilege; it came with responsibility. He was to become the head of the family upon his father's death, responsible for caring for the women and any unmarried siblings.

The reason for this is given: "for he is the first of his vigor." He is the beginning of the father's strength, the firstfruits of his posterity. His position is a matter of historical fact, not feeling. The verse concludes by stating that "the legal judgment for the firstborn belongs to him." The right, the privilege, the inheritance of the firstborn is his by law. It is not the father's to give or take away at a whim. This protected the son of the unloved wife from being disenfranchised. It protected the stability of the family line. And ultimately, it pointed to the great Firstborn, Jesus Christ, whose inheritance is not based on our fickle love for Him, but on His status as the only begotten Son, the first of His Father's vigor, to whom all judgment and all inheritance rightly belong.

Application

First, we see that God's law is intensely realistic. It does not legislate for a perfect world; it brings righteousness to bear on our fallen one. It recognizes that our hearts are prone to sinful favoritism and partiality, and it erects legal barriers to protect the vulnerable from our whims. In our families and churches, we must be on guard against this same sin, ensuring that justice and righteousness, not personal affinities, govern our decisions.

Second, this law teaches us to submit our feelings to God's revealed will and objective truth. The father's love for one wife was real, but it was not the ultimate reality. The ultimate reality was the birth order established by God's providence. We are constantly tempted to make our feelings the standard of truth. This passage commands us to do the opposite: to bend our feelings and our actions to the truth of God's Word and His world.

Finally, we must see the gospel here. The right of the firstborn is a central theme in Scripture. Israel was God's firstborn son. But the ultimate firstborn is Jesus Christ. He is the beloved Son, and yet for our sakes, He was treated as the unloved, cast out and crucified. He is the true "first of his vigor," the firstborn from the dead. And because God the Father "recognized" Him by raising Him from the dead, He has received the inheritance, all authority in heaven and on earth. And by faith in Him, we who were unloved, who had no claim on the inheritance, are adopted into God's family and become co-heirs with Christ. Our standing is secure not because of how well we are loved by the world, or even by our own fickle hearts, but because we are in Him, the true and rightful Firstborn.