The Prodigal God: Recovering the Heart of the Christian Faith

Timothy Keller’s 2008 work of Christian apologetics, The Prodigal God: Recovering the Heart of the Christian Faith, offers an in-depth exploration of Jesus’s Parable of the Prodigal Son from the Gospel of Luke. Keller reframes the story as the Parable of the Two Lost Sons, arguing that it is a narrative about two distinct but equally flawed paths of spiritual alienation. The book is addressed to both irreligious seekers (younger brothers) and devout insiders (elder brothers), contending that both are estranged from God and in need of his reckless, or “prodigal,” grace. The central analysis focuses on themes such as the idea that Both Brothers Are Lost, the concept of Sin as Self-Salvation, and the necessity of Costly Grace and the True Elder Brother.

Keller (1950-2023) was an influential theologian and the founding pastor of Redeemer Presbyterian Church in New York City, a ministry known for engaging a secular, urban population. This context shapes the book’s approach, which seeks to distinguish the Christian gospel from both religious moralism and secular relativism. Published shortly after his bestselling The Reason for God, this book continues Keller’s project of presenting orthodox Christian doctrine to a contemporary audience.

This guide is based on the Penguin edition, first published in 2011. 

Content Warning: The source material and this guide feature depictions of death, animal death, racism, religious discrimination, graphic violence, sexual content, substance use, mental illness, and illness.

Summary

This book explains the Christian gospel to non-believers (“younger brothers”) and longtime believers (“elder brothers”) using the Parable of the Prodigal Son. The author argues that the parable’s common name is a misnomer, suggesting that “The Two Lost Sons” is more fitting because the story is about both brothers and the father. He further clarifies that “prodigal” does not mean “wayward” but “recklessly spendthrift,” applying the term to the father’s lavish grace as well as the younger son’s spending.

In the Bible, Jesus tells the parable to two groups: irreligious social outcasts (younger brothers) drawn to his message, and morally upright “Pharisees” (elder brothers) angered by his acceptance of sinners. However, Keller argues that the parable is largely aimed at the Pharisees to challenge their self-righteousness. He notes that early Christianity was considered a “non-religion”—lacking temples and sacrifices, its followers were called “atheists” by Romans—a stark contrast to its modern perception as a moralistic religion. The author argues that if today’s churches repel “younger brothers,” it is because they are filled with “elder brothers” who, overly concerned with rules and rituals, are not preaching Jesus’s message.

Keller frames the parable as unfolding in two acts and explicates each with reference to the era’s cultural norms. The first follows the younger brother, who disrespectfully demands his inheritance, effectively wishing his father dead. The father endures this, though it would have entailed liquidating a third of his estate. The son squanders the money in a distant country and ends up destitute, feeding pigs. Realizing his mistake, he grows contrite and plans to return as a hired man. However, rather than forcing his son to earn his way back into his good graces, the father immediately embraces him. Interrupting the son’s confession, the father orders a robe, ring, and sandals and kills the fattened calf for a feast, symbols of full, unconditional restoration. 

This act shows the freeness of God’s grace, but the next reveals its cost by focusing on the elder brother. Learning of the celebration for his returned brother, he grows furious and refuses to enter, publicly shaming his father. When the father comes out to plead with him, the elder brother complains that his years of obedient service have gone unrewarded. The father gently reminds him that he has shared all he owns with his son but explains that they must celebrate because his brother has effectively returned from the dead. The parable ends here, leaving the elder brother’s choice unresolved as a direct challenge to the Pharisees.

Keller contends that the brothers represent two flawed paths to happiness: The younger brother prioritizes self-discovery, while the elder brother chooses moral conformity. Both are spiritually “lost” because they want the father’s possessions, not the father himself. Likewise, each resents the father’s authority and seeks to evade it—one by breaking the rules, the other by keeping them. Read allegorically, each brother thus seeks fulfillment, or even salvation, by pursuing his own agenda. Keller therefore clarifies that Jesus defines sin not as merely breaking rules but as putting oneself in God’s place as Savior and Lord. In this sense, both moralism and self-indulgence are forms of rebellion.

However, Keller suggests that moralism, or “elder-brother lostness,” is particularly dangerous because it is self-deceiving. Its signs include deep anger when life goes wrong (born from a sense of entitlement), a superior, unforgiving spirit, and joyless, fear-based obedience. That elder brothers view salvation as something they can (and therefore must) “earn” reveals that they lack assurance of God’s love, leading to insecurity, guilt, and a dry prayer life. Escaping this lostness requires God’s initiating love and a repentance that rejects not only sin but also the self-righteousness that can lie behind good deeds. 

In reflecting on what allows this transformation to occur, Keller notes that the Parable of the Prodigal Son differs from the two that immediately precede it in a significant way. Unlike the Parables of the Lost Sheep and Lost Coin, where the owner searches for something he has lost, no one seeks the younger son. Keller suggests that the elder brother should have gone. Moreover, it is notable that the son’s restoration is not free; it is paid for from the estate now legally belonging to the elder brother, implying that redemption always comes at a cost. Taken together, Keller argues, these points create a yearning for a “True Elder Brother”: Jesus himself. Jesus came from heaven to earth, paying the infinite cost of his life to rescue humanity.

Keller also notes that the parable reflects the biblical theme of exile and homecoming. He argues that there is a universal longing for home that actual homes rarely satisfy, echoing humanity’s exile from Eden. It was because of this exile that Jesus lived a life of ultimate exile, culminating in his crucifixion outside the city gates, thus redeeming humanity’s sin. His resurrection promises a final homecoming: a great feast at the end of history in a renewed world where all suffering is eliminated.

Observing that the Parable of the Prodigal Son also ends in a feast, Keller argues that the feast metaphor illustrates four aspects of the Christian life. Salvation is experiential, involving a subjective “taste” of God’s love, material, affirming the goodness of the physical world and motivating Christians to fight injustice and suffering, individual, as personal growth requires continually “feeding” on the gospel to replace fear with grateful love, and communal, since knowing Jesus fully requires involvement in a church. The book concludes with Keller’s reading of Isak Dinesen’s “Babette’s Feast,” where a meal heals a joyless religious community, highlighting the failure of both the aesthetic (younger brother) and ethical (elder brother) life paths. Keller argues that Jesus is the true feast, offering a third way that leads to God’s ultimate banquet.