The new heart and new life that Christ gives is the beginning of an entirely new tree. In the gospel, our true and eternal identity is in Christ, even though we still battle with the patterns and baggage of our old ways. Rather than simple self-discipline and willpower, though, the real source of change is new faith and affections in our hearts, redeemed desires, and transformed worldviews—all given to us in Christ.

“But isn’t it just a lust problem?” Mike asked. I was explaining to Mike the Harvest USA Tree Model, the core content of our ministry to both individuals and churches. Mike wanted to believe what I was saying about the deeper aspects of his sin. It gave him hope that there was a path to victory in his fight against the porn habit he’d been losing for years, because willpower certainly hadn’t worked. His objection revealed a problem that most of us encounter when thinking about our sin.

Mike’s question forces us to seek a more complete understanding of sin. We tend to think of sin in simple ways that only scratch the surface: I’m tempted; I fall; I repeat. But a biblical view of sin goes much deeper. This is what our Harvest USA Tree Model illustrates.

Jesus describes sin as having a source deep within us, in the heart, the epicenter of where our intellect, will, and affections all converge. In Matthew 15:18–19, Jesus said, “But what comes out of the mouth proceeds from the heart, and this defiles a person. For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false witness, slander.” Thinking of our hearts as part of a tree originates from Jesus’ words in Luke 6:43–45: “For no good tree bears bad fruit, nor again does a bad tree bear good fruit, for each tree is known by its own fruit. For figs are not gathered from thornbushes, nor are grapes picked from a bramble bush. The good person out of the good treasure of his heart produces good, and the evil person out of his heart produces evil, for out of the abundance of the heart his mouth speaks.” Building upon these verses, our Tree Model pictures the heart as the source of a tree, the seed.

The Seed: Our Hearts

The most basic characteristic of the seed, or heart, is that it is fallen. The word “autonomy” summarizes the sinful inclination of our hearts. We desire self-rule rather than being ruled by the authority and care of God. Our desire for autonomous independence from God affects every aspect of our lives. It shapes our reactions to our circumstances and experiences; it skews our deepest desires; it taints our functional worldviews. These are the inner workings of sin that bear fruit in what we do. The following three make up the other elements of the tree: the soil, the roots, and the trunk.

The Soil: Our Circumstances and Experiences

The soil is the context for the seed. The parents to whom we were born, our families, and our peers are all part of the soil. It is all the things those people do to us or for us—or neglect to do. It is everything that happens to us, good or bad. We are praised, abused, affirmed, attacked, protected, or wounded. We experience trauma and suffering, or we live in shelter and safety. Together, these experiences comprise the context in which our fallen hearts are active.

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