The Arithmetic of a Godly Life Text: Psalm 90:12-17
Introduction: The Great Turn
Psalm 90 is the great prayer of Moses, the man of God. It is a psalm that begins in the heights of God's eternity and descends into the depths of man's frailty. The first eleven verses are a stark and unflinching meditation on the brevity of human life under the wrath of a holy God. We are dust. We are like grass that springs up in the morning and by evening is withered and cut down. Our days are consumed by God's wrath, our years finished with a groan. It is a bleak picture, and if the psalm ended at verse 11, it would be a psalm of blackest despair.
But it does not end there. At verse 12, the psalm makes a great turn. It pivots from meditation to petition, from a diagnosis of our condition to a plea for divine intervention. Having laid out the grim reality of our mortality, Moses does not throw up his hands in nihilistic surrender. He does not advise us to eat, drink, and be merry for tomorrow we die. No, he gets on his knees. He turns from staring at the problem to addressing the only one who has the solution. This is the great mark of a man of God. He looks reality square in the face, no matter how grim, and then he immediately turns his face to God.
This second half of the psalm is where the gospel light begins to break through the clouds of our mortality. It is a series of requests that are breathtaking in their audacity. Moses, having just described us as fleeting wisps of smoke, now asks for a heart of wisdom, for God's satisfying lovingkindness, for gladness to match the affliction, for God's majestic work to be shown to us, and for the favor of God to establish the work of our hands. He asks that our fleeting, dusty lives might be filled with eternal significance. This is not the prayer of a man who believes we are meaningless accidents. This is the prayer of a man who knows that the eternal God can and does invade our temporal reality with grace, glory, and permanence.
We live in an age that is terrified of the truths in the first half of this psalm and is therefore utterly ignorant of the glorious requests in the second half. Our culture frantically tries to deny death, to extend life by any means, to distract itself with endless entertainment, all to avoid the simple fact that our days are numbered. But because they will not number their days, they cannot gain a heart of wisdom. They are left with foolishness, chasing after the wind. We, as Christians, must be different. We must learn the holy arithmetic taught here. We must learn to count, so that we might truly live.
The Text
So teach us to number our days, That we may present to You a heart of wisdom.
Return, O Yahweh; how long will it be? And be sorry for Your slaves.
O satisfy us in the morning with Your lovingkindness, That we may sing for joy and be glad all our days.
Make us glad according to the days You have afflicted us, And the years we have seen evil.
Let Your work appear to Your slaves And Your majesty to their sons.
Let the favor of the Lord our God be upon us; And establish for us the work of our hands; Establish the work of our hands.
(Psalm 90:12-17 LSB)
The Foundational Request (v. 12)
The pivot of the psalm rests on this first petition.
"So teach us to number our days, That we may present to You a heart of wisdom." (Psalm 90:12)
Notice the "So" at the beginning. It connects this request directly to the preceding meditation on our frailty. Because our lives are short, because we are like grass, because we live under the shadow of God's wrath against sin, therefore, teach us this divine arithmetic. This is not a request for God to tell us the exact date of our death. It is a plea for a particular mindset, a Spirit-given perspective. To number our days means to live with a keen awareness of our finitude. It is to remember that we are not proprietors of our time, but stewards. We have an allocation, and it is not infinite.
The world's response to this reality is "carpe diem," seize the day for your own pleasure. The biblical response is "redime tempus," redeem the time for God's glory. Numbering our days is not a morbid obsession with death; it is the necessary prerequisite for a life of meaning. A man who thinks he has forever to get right with God will likely never do it. A student who thinks the exam is a decade away will not study. It is the deadline that focuses the mind. Our mortality is the deadline God has given us, and He wants us to be intensely aware of it.
And what is the goal of this numbering? "That we may present to You a heart of wisdom." The Hebrew is literally "that we may bring a heart of wisdom." Wisdom, in the Bible, is not about having a high IQ. It is skill in the art of godly living. It is knowing the fear of the Lord. And this wisdom is the direct result of understanding our place in the world. When we know we are creatures, not the Creator, and that our time is short, we stop wasting it on trivialities. We stop investing in things that will burn. We begin to seek first the kingdom of God and His righteousness. A man who numbers his days aright does not spend his life rearranging deck chairs on the Titanic. He is looking for the lifeboat. And the lifeboat is Christ.
The Cry for Presence and Pity (v. 13)
Having asked for wisdom, Moses now cries out for God Himself.
"Return, O Yahweh; how long will it be? And be sorry for Your slaves." (Psalm 90:13)
This is the cry of a covenant people who feel the sting of God's apparent absence. The forty years in the wilderness were a period of judgment. The people felt the distance that their sin had created. "Return, O Yahweh" is a plea for revival, for a renewed sense of God's favor and presence. The question "how long?" is the constant cry of the saints in Scripture. It is not a question of faithless impatience, but of faithful longing. It is the cry of a bride waiting for the bridegroom.
And then the stunning request: "And be sorry for Your slaves." The Hebrew word for "be sorry" is the word for repent or relent. It means to have compassion, to change one's disposition from wrath to mercy. Of course, God does not "repent" in the human sense of changing His mind because He made a mistake. He is immutable. But from our perspective, when God turns from judgment to grace, it is as though He relents. This is the language of covenant relationship. Moses is appealing to God on the basis of their relationship. We are "Your slaves," Your servants. He is arguing from God's character to God's character. "You are a compassionate God; therefore, have compassion on us." This is the very argument that prevailed when Moses interceded for Israel after the golden calf incident. It is a prayer that God will act like Himself.
The Cry for Joy (v. 14-15)
The next request is for a deep, satisfying joy that can only come from God.
"O satisfy us in the morning with Your lovingkindness, That we may sing for joy and be glad all our days." (Psalm 90:14)
The word for lovingkindness is "hesed," that great covenant word that means steadfast love, mercy, and faithfulness. Moses asks that God would satisfy them, glut them, with His hesed. And he asks for it "in the morning." After the long night of wandering and judgment, he prays for the dawn of God's favor. This is a prayer for a joy that is not dependent on circumstances. Only God's covenant love can truly satisfy the human heart. Everything else is like drinking salt water. The more you drink, the thirstier you get. But the one who drinks of God's hesed will find a spring of water welling up to eternal life.
The result of this satisfaction is gladness and joyful song, not just for a moment, but "all our days." This is not a fleeting happiness, but a deep-seated, durable joy. It is the joy that Nehemiah spoke of, "the joy of the Lord is your strength." It is a joy that can sing in the middle of a prison, as Paul and Silas did.
"Make us glad according to the days You have afflicted us, And the years we have seen evil." (Psalm 90:15)
This is one of the most audacious prayers in all of Scripture. Moses is not just asking for the affliction to stop. He is asking for a gladness that is commensurate with the sorrow. He is asking for a blessing that is directly proportional to the trial. He is essentially saying, "Lord, for every day of misery in this wilderness, give us a day of exultation in the promised land. For every year we have seen evil, give us a year of seeing your goodness." This is not a demand for compensation. It is a profound statement of faith in God's ability to redeem suffering. It is a postmillennial prayer in miniature. It assumes that God is not just in the business of cleaning up messes, but of turning those messes into monuments of His grace. The apostle Paul echoes this very sentiment: "For our light affliction, which is but for a moment, is working for us a far more exceeding and eternal weight of glory" (2 Corinthians 4:17). God does not waste our sorrows. He invests them, and the return on investment is a weight of glory.
The Cry for Glory and Permanence (v. 16-17)
The final petitions are for God's work to be seen and for our work to be established.
"Let Your work appear to Your slaves And Your majesty to their sons." (Psalm 90:16)
Moses asks that God's great work of salvation and judgment would be made manifest to His people. They had seen God's work in the plagues on Egypt and at the Red Sea, but now they are in the desert. They need a fresh vision. And he asks that God's "majesty," His glory and splendor, would be revealed to the next generation, "to their sons." This is a prayer for covenant succession. True faith is never content to be a one-generation affair. A godly man wants his children and grandchildren to see an even greater display of God's glory than he has seen. He wants them to stand on his shoulders to get a better view of the coming kingdom.
The psalm concludes with a double request for God's favor to rest upon and establish our work.
"Let the favor of the Lord our God be upon us; And establish for us the work of our hands; Establish the work of our hands." (Psalm 90:17)
This is the capstone of the entire prayer. After meditating on the fact that we are dust and our lives are a fleeting breath, Moses asks for permanence. He asks that the "favor" or the "beauty" of the Lord would be upon us. This is a prayer that our lives and our work would reflect the very character and beauty of God Himself. We are to be little mirrors reflecting His glory into the world.
And then the plea, repeated for emphasis: "establish the work of our hands." What is the work of our hands? It is everything we do in obedience to Him. It is raising children, building houses, writing books, planting churches, running businesses, making laws. In ourselves, all this work is as fleeting as the grass. It is a puff of smoke. But Moses prays that the eternal God would reach down and impart His own permanence to our frail efforts. He asks God to take our little bits of fog and mist and glorify them, to establish them forever.
This is the heart of the Protestant work ethic. All of life is to be lived Coram Deo, before the face of God, and all our labor, when done in faith, has eternal significance. This prayer is impossible for God to answer apart from the incarnation. It is only in Jesus Christ, the one whose life had the full favor and beauty of the Lord upon it, that our ugly, transient lives can be made beautiful and permanent. He took our sin, our frailty, and our death to the cross, and in His resurrection, He offers us His righteousness, His glory, and His permanence. Because He was raised, our labor in the Lord is not in vain. He is the one who establishes the work of our hands.
Conclusion: From Dust to Dominion
This psalm begins with man as dust and ends with man asking for his work to be established forever. This is the story of the gospel. In Adam, we are dust, blown away by the wind of God's judgment. Our lives are short, and our work is futile.
But in Christ, the second Adam, everything is transformed. God teaches us to number our days, not so that we would despair, but so that we would flee to the one who is the Lord of all our days. He satisfies us with His steadfast love, His hesed, demonstrated supremely at the cross. He gives us a joy that swallows up our affliction. He shows us His glorious work of new creation. And He takes the humble, faithful work of our hands, done in His name, and He establishes it. He weaves it into the fabric of His eternal kingdom.
Therefore, we do not lose heart. Though our outer self is wasting away, our inner self is being renewed day by day. We number our days, and we find that they are in His hands. We look at our work, and we ask for His favor. And we know that because of the finished work of Jesus Christ, this audacious prayer of Moses is not only possible, it is guaranteed. God will establish the work of our hands, and His beauty will be upon us, forever.