The Balance of Spiritual Growth: Inside and Out

One of the most exciting parts of the Christian life is spiritual growth. As we walk with Christ, we begin to think differently, love differently, and live differently. But where does this growth come from? Is it something we produce ourselves, or does it come from God?

To help answer this question, we can think about two concepts: exogenous growth and isogenous growth.

These have been a controversy in Church teaching for years, as most seminaries tell students that they must teach exogenous only as all change comes from God and needs no external forces to reach the spiritual destination.

I do not believe this to be absolutely true.

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What Is Exogenous Growth?

The word exogenous means “coming from outside.”

In the Christian life, exogenous growth refers to the ways God works in us through influences that come from outside ourselves. These include:

• Reading God’s Word
• Listening to biblical teaching
• Fellowship with other believers
• Prayer
• The work of the Holy Spirit
• Christian mentors and discipleship

Illustration:
Think of a plant in your garden. Even if it has strong roots, it still needs sunlight, water, and nutrients from the soil. These things come from outside the plant, yet they are essential for growth. Similarly, Christians need God’s Word, His Spirit, and fellowship to grow spiritually.

Jesus taught, “Apart from me, you can do nothing” (John 15:5). Spiritual growth begins with God’s grace reaching into our lives.

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What Is Isogenous Growth?

The word isogenous refers to growth that comes from within.

When a person trusts in Christ, God places His Spirit within them. A new nature begins to develop. As believers mature, they increasingly display qualities such as:

• Love
• Joy
• Peace
• Patience
• Kindness
• Faithfulness

Illustration:
Imagine an apple tree. Because it is an apple tree, it naturally produces apples. It doesn’t need someone to push the apples out—it is in its nature. In the same way, Christians produce godly character because Christ lives within them.

Paul describes believers as a “new creation” (2 Corinthians 5:17). God transforms us from the inside out.

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Why We Need Both

Some Christians focus only on external influences—they attend church, listen to sermons, and read books—but they never allow God to change their hearts.

Others focus only on internal feelings, neglecting Scripture, fellowship, and teaching.

Healthy Christian growth requires both.

Illustration:
Think of a tree again. Sunlight and water (external) feed it, but the tree also produces leaves and fruit (internal). Both are necessary for full growth.

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A Practical Example

Imagine a young believer who attends a Bible study every week.

• Exogenous growth: The Bible teaching, encouragement from friends, and prayer support represent help coming from outside.
• Isogenous growth: As the believer begins to show more patience, forgiveness, and love in daily life, this is growth coming from within.

The two work together. External nourishment fuels internal transformation.

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Growing in Grace

The goal of Christian growth is not just gaining knowledge but becoming more like Jesus.

As you spend time in God’s Word, pray faithfully, and walk with other believers, God uses these external influences to strengthen the new life He has placed within you.

Spiritual growth is both a gift and a process. God provides what we need from the outside, and His Spirit produces lasting change on the inside.

Paul wrote, “He who began a good work in you will carry it on to completion until the day of Christ Jesus” (Philippians 1:6).

Illustration:
Picture a seedling growing into a strong tree. Sunlight, water, and nutrients (exogenous) feed it, but the life and growth inside the seed (isogenous) produce leaves, branches, and fruit. The Christian life works the same way—God works both outside and inside us to help us grow in grace.

                CHRISTIAN GROWTH
                       │
      ┌────────────────┴────────────────┐
      │                                 │
      ▼                                 ▼

EXOGENOUS GROWTH                  ISOGENOUS GROWTH

(From Outside Us) (From Within Us)

                                        
  God's Word                     New Life in Christ
      │                                  │
                                       
  Bible Study                       Love
      │                                  │
                                       
    Prayer                            Joy
      │                                  │
                                       
  Fellowship                         Peace
      │                                  │
                                       
Holy Spirit's Work                  Patience
      │                                  │
      └──────────────┬───────────────────┘
                     │
                     ▼

                SPIRITUAL FRUIT
          Becoming More Like Jesus

══════════════════════════════════════════
EXOGENOUS GROWTH
(Nourishment from outside)

  Sunlight = God's Word
  Rain = Prayer
  Soil Nutrients = Fellowship
  Life-Giver = Holy Spirit

Exogenous Growth: What God provides to us.

Isogenous Growth: What God produces in us.

Result: A mature believer who reflects Jesus to the world.

Study further in God’s Word with my just released book: Growing in Grace: Exploring the Parables of Jesus