In this bonus episode of Defragmenting, recorded at the Gospel Coalition's 2025 National Conference, Dr. Keith Plummer talks with New Testament scholar Dr. Matt Harmon and Cairn's own Distinguished Professor of Old Testament, Dr. Gary Schnittjer, about their book How to Study the Bible's Use of the Bible: Seven Hermeneutical Choices for the Old and New Testaments. They explain how the Old Testament use of Scripture is integral to understanding the New Testament author's use of Scripture.

Later in the episode, we'll also hear from Dr. Michael Keller, Senior Pastor of Redeemer, Lincoln Square, about what it means to faithfully contextualize the gospel and why it's so important. He also gives us a preview of a book that arose from conversations between him and his dad, Pastor Tim Keller, before his death, as well as unpublished writings by Tim following his going to be with the Lord. At the time of recording, the title was Unsettled. We know now it's The Stories We Live By: How Jesus Critiques and Completes What Our Culture Tells Us.

Matt Smethurst says the aim of his book, Tim Keller on the Christian Life is to synthesize and distill Tim Keller’s best teaching on the Christian life. We believe he succeeded at that task, and we’re not alone. World magazine selected it as its 2025 Book of the Year, stating, “This well-written book will convict but also encourage Christians who read it, helping them as they pray, pursue friendships, go to work, consider how to help their poor neighbors, and endure suffering themselves.” Pastor Smethurst joined Dr. Keith Plummer to talk about why he wanted to write the book and some of the recurring themes of Tim Keller’s thinking, writing, and preaching about following Jesus.

Might a popular understanding of Paul’s words in Romans 7:14-25 contribute to a learned helplessness with respect to sin in the lives of many Christians? New Testament scholar Dr. Joseph Dodson believes the answer is yes and explains why in his book Conquerors Not Captives: Reframing Romans 7 for the Christian Life. In this episode, he joins Dr. Keith Plummer to discuss his take on this much-contested passage.

The adverse effects of a screen-immersed life on children and teens becomes harder to ignore on what seems to be a daily basis. What are parents to do? In her book The Tech Exit: A Practical Guide for Freeing Kids and Teens from Smartphones, Clare Morell offers well-researched and hope-giving answers. She joined Dr. Keith Plummer to talk about the dangers screen immersion, the inadequacy of screen limiting and parental control software, how to prepare for a family digital detox, and how and why to fill the time previously consumed by fixation on devices. This informative and encouraging exchange is not foremost about saying no to digital tech but rather, about acknowledging and embracing what God has made us for.

As the hymn writer noted, our hearts have a proneness to wander from the Lord we love. On account of this inclination, God, through the writer of the book of Hebrews, calls us to “pay much closer attention to [the gospel] lest we drift away from it.” In his book Lest We Drift, Jared C. Wilson explains the subtle yet powerful ways that even those who claim to be “gospel-centered” can stray from the purity of the gospel of grace and the counterfeits we drift toward in its place. He joined Dr. Keith Plummer to talk about this and more.

One doesn't have to look too hard or too far to recognize the church's shortcomings. But according to Brad Edwards, author of The Reason for Church, these obvious flaws aren't the main reason people dismiss the idea that church helps humans flourish. Edwards argues that both Christians and non-Christians have absorbed two powerful assumptions: anti-institutionalism and radical individualism. These beliefs make many view the church with cynicism and suspicion, preventing people from recognizing how its work and witness can help address our deepest needs. In this episode, he joins Dr. Keith Plummer to discuss these cultural assumptions and how even committed Christians can mistake these ideas for genuine biblical faith.

The Edmiston Center focuses on Christian endurance in the midst of competing cultural narratives. Mrs. K.A. Ellis, its director, joined Dr. Keith Plummer to talk about how she came to Christ and the people and things God used to form her heart for Christians experiencing persecution around the world. What different forms does persecution take, and despite these differences, what commonalities underlie them? What can Christians in the West learn from how Christians around the world and across time have persevered in the face of severe opposition? How can American Christians conquer cultural anxiety? Karen answers these questions as well as whether American Christians are being persecuted. She and Dr. Plummer also discuss what led her to “jump ship” from X (Twitter).

In his book, The Body God Gives: A Biblical Response to Transgender Theory, Dr. Robert S. Smith offers a biblically grounded critique of transgender theory’s central claim that there is no inherent connection between the sexed body and the gendered self. In this episode, he joins Dr. Keith Plummer to discuss how he came to be interested in this subject; some of the factors that have led to the current confusion about the relationship between biological sex and gender; and what biblical revelation reveals about the significance of embodiment for sexuality, marriage, and personal identity.