Podcast Summary: "Is Theology Practical or Speculative?"

Podcast: Doctrine Matters with Kevin DeYoung
Host: Kevin DeYoung (Crossway)
Episode Date: January 13, 2026

Episode Overview

In this episode of Doctrine Matters, Kevin DeYoung tackles an age-old theological question: Is theology primarily practical or speculative? Drawing from the rich history of Christian thought, DeYoung explores the historical context and relevance of this distinction, referencing key theologians such as Thomas Aquinas and Francis Turretin. He also discusses the relationship between faith and reason and the role of philosophy in theology, making the case that these categories—practical and speculative, faith and reason—are not opposites, but partners in understanding God and living a faithful Christian life.

Key Discussion Points & Insights

1. The Central Question: Speculative vs. Practical Theology

• Framing the Question ([00:50])

  • DeYoung opens by noting that, to most modern listeners, the answer seems obvious—of course theology is practical! The practical feels positive, while speculative often carries negative connotations of abstract or irrelevant debate.
  • He cautions, however, that theologians mean something deeper by these terms.

    "Most people listening to this think that's kind of a ridiculous question because obviously theology is practical. That's chiefly what it is. ... But that's not what theologians have meant by this question. And it's actually a surprisingly relevant question. It's not as simple as it sounds." ([01:10])

• Historical Context

  • Thomas Aquinas (13th c.):
    • Saw sacred doctrine as a "speculative science" because its main concern is knowing God, not just human actions.

      "Aquinas said the goal of theology is the perfect knowledge of God in which consists eternal bliss." ([02:20])

    • He admitted it is ‘some of both.’
  • Francis Turretin (17th c.):
    • DeYoung’s favorite, described theology as "mixed"—both theoretical (speculative) and practical.

      "He says that true theology is mixed. I like that. So he's giving some both. And he said it is partly theoretical and partly practical." ([03:05])

    • The mysteries of the faith are meant to lead to action, yet contemplation of God's nature is valuable in itself.

• Definitions and Misconceptions

  • Speculative does not mean irrelevant or idle, but refers to the pursuit of understanding God for its own sake.

    "It doesn't mean someone just leaning back in their chair and stroking their chin ... No, what he means is a theological inquiry is worthwhile on its own if it teaches us something about God." ([04:00])

• Danger of "Practical Only" Theology

  • Turretin warned that heretical movements in his day pushed for exclusively practical theology to avoid difficult doctrines (Trinity, Incarnation, etc.), leading to errors like universalism and Unitarianism.

    "We’re right in our day to be a little nervous if someone says the only theology that counts is the theology that can be put into practice." ([05:50])

  • Sometimes, the highest "practicality" is simply "to behold God."

• Conclusion on the Central Question

  • Theology should be both speculative and practical; these are not opposed but integrated.

    "So is theology speculative or is it practical? We want to say that it is both. It's mixed and we want to aim at both." ([06:55])

2. Faith & Reason: Friends, Not Enemies

• Debate Overview ([07:10])

  • There is a misconception that faith and reason must be in conflict—either reason undermines faith or faith is seen as blind acceptance.

    "Throughout the history of the Church, ... the best theologians have always insisted that faith and reason, though they operate in different ways, are ultimately not in conflict." ([07:45])

• Turretin’s Markers on Reason:

  1. Reason is Not the Ultimate Judge:
     • "Human reason is not the rule by which the doctrines of Christianity are to be judged." ([08:10])
     • Reason doesn’t arbitrate what can be believed; instead, it functions instrumentally.
  2. Instrumental Use of Reason:
     • We use reason to understand and explain doctrine, not to set its boundaries.

       "Reason does not have the principal office in matters of faith, but has an instrumental one. ... It’s not the goalie." ([08:40])

  3. Drawing Needed Inferences:
     • Using reason, Christians are right to draw necessary consequences from Scripture (example: Jesus arguing for resurrection).

       "Jesus proves his defense of the resurrection by saying God is the God of the living, not the dead." ([09:40])

  4. Against Blind Faith (Fideism):
     • Christians are not called to fideism—belief without reason or evidence.

       "Fideism is just believing, just willing yourself. ... That's not how we should think of the Christian life. Rather, Christian faith goes together with reason." ([11:00])

  • Distinguishing Incomprehensible from Impossible:

    "We have to distinguish between something which is incomprehensible and something that is impossible." ([11:40])

    • Some mysteries transcend our comprehension but are not contrary to reason.

3. The Proper Place of Philosophy

• Philosophy as Handmaiden

  • Philosophy and reason can aid theology, provided they remain subordinate.

    "At its best, reason and philosophy can be valuable handmaidens to theology." ([12:25])

    • They help explain, defend, and sometimes lead others to faith, but must not displace revelation.

  • God’s Character and Human Limitation:

    "Because our God is a God of light and not confusion. He's a God of truth and not error. ... And though there will be many mysteries that are beyond our final comprehension in this life, we want to appropriate them and understand them as best we can." ([13:10])

Notable Quotes & Memorable Moments

• On the Value of Theology

  "Doctrine doesn't count for much if it doesn't sink down into the deepest part of us. We want truth that leads to godliness. That's Titus 1:1."
  — Kevin DeYoung ([03:50])

• On Contemplation as Practical

  "Sometimes that chief relevance is simply to behold God, to know more of what God is like in the face of Christ."
  — Kevin DeYoung ([06:10])

• On Faith and Reason

  "Faith and reason are friends, not enemies."
  — Kevin DeYoung ([13:40])

Timestamps for Key Segments

• [00:50] — Introduction of main episode question
• [02:20] — Aquinas's view on speculative theology
• [03:05] — Turretin on theology as “mixed”
• [05:50] — Warnings on “practical only” theology
• [06:55] — Synthesis: theology is both speculative and practical
• [07:10] — Transition to faith and reason
• [08:10] — Reason’s role as instrumental in theology
• [09:40] — Jesus’ use of reason in Scripture
• [11:00] — Critique of fideism (blind faith)
• [12:25] — Philosophy as a handmaiden to theology
• [13:10] — The character of God and embracing mystery
• [13:40] — Conclusion: faith and reason as partners

Summary Takeaways

• The question of whether theology is practical or speculative is not trivial—both aspects are essential for a mature, biblical theology.
• Misunderstanding these terms can lead to error; theology must inform both contemplation (knowing God) and practice (obeying God).
• Faith and reason are not adversaries; reason serves as an instrument in understanding faith, and philosophy can aid but not dominate theology.
• Christians should value both deep doctrinal reflection and practical application, holding them together for a robust faith.

This episode offers a thoughtful, historically grounded perspective for anyone wondering how the "why" and "how" of theology go together—encouraging listeners to behold God's truth, and letting that truth transform life in practice.