Why did God allow humans to fall into sin? To answer that question, we need to think of redemption. If our redemption (and glorification) is merely a return to the garden-of-Eden-state, then the fall makes little sense (hardly the felix culpa it’s known to be). On the other hand, if our redemption eventually brings us to a state that is better than our original state in Eden, the fall begins to make sense. In that way, the fall is a tool in the hands of the Redeemer (to borrow Paul David Tripp’s title) to create the maximally blessed creature. In this way, we can conceive of some of the ways in which God’s sovereignty fits with Adam’s fall.
Before we consider some options, a disclaimer is in order. Our consideration of God’s decrees can never be perfect since we look upon eternally considered actions with finite minds. We cannot fully understand God’s decisions any more than a child can understand her parents’ desire to see her eat her vegetables—the growth and planning are too far from our perception. But, like explaining things to a child, God can shade in the corners, so we get a rough idea of the general picture.
What are some of the benefits that the fall produced for humanity? What would we miss out on if Adam and Eve never fell? Below are five things that the fall produced which would not occur in a world without the fall:
The fall allowed Adam and Eve (and their progeny) to experience the grace of God. Their state before the fall was that of the covenant of works. God told them that they would maintain perfect blessedness if they abstained from eating of the tree of the knowledge of Good and Evil. That is, their blessedness was tied to their ability to abstain from the sin of commission (eating of the tree) and omission (failing to be fruitful and multiply). Therefore, their fall enabled them to experience the unmerited grace of God (John Murray, I have been told, would disagree and say their original state was also the covenant of grace since no one can deserve to be created by God, but his is a minority position). This grace experienced due to the fall is most perceptible in the incarnation and work of Jesus Christ, which would not have been necessary if man never fell (one might compare the idea of Christological Supralapsarianism).
It seems we would not be able to fully grasp the concept of love without sin. Jesus says, “Greater love has no one than this, that one lay down his life for his friends” (John 15:13, LSB). This verse seems to indicate that to understand the greatest type of love; we must have the sin that makes sacrificial death necessary. This is, of course, tied to the first point, as should be expected—we cannot truly understand grace without truly understanding love.
The fall enabled humanity to experience the wrath of God against sin. This experience of wrath might not seem beneficial, but the Bible says it is. The church in Revelation 18 will sing praises as the specter of God’s wrath is poured out (cf. Jonathan Edwards’s sermon on Rev 18:20). In this way, fallen and redeemed humanity will witness more of God’s infinite perfections than they would have if mankind never fell.
Adam and Eve were perfect but in a mutable state of perfection. Obviously, their state could change because it did. They were perfect, and they became sinful. Redeemed and glorified man, on the other hand, will be in an immutable state of perfection (this is Augustine’s non posse peccare). Without the fall, it seems that the fall would always be possible. With the fall and redemption, a second fall becomes impossible (Rom 8:35-39). The natural question is why God allowed the fall to be possible, but this question may be answered by the first three points.
Though Adam and Eve did relate beautifully with God, they were not as completely unified with Him as a fallen and redeemed man. This greater union is because redeemed man has been unified with Christ. Christ is not only God, but he is also man. Therefore, this movement on Christ’s part (cf. WCF 7.1) has brought about a full fruition of union with God. Without Christ’s incarnation, man and God are more separated than they are in Christ. Of course, God could become incarnate without sin (perhaps He did in OT theophanies), but this incarnation would not bring about as intimate a union as is required in the double imputation—all of who we are as sinful people was imputed into Christ, and all of who He is as righteous was imputed into us. This full-scale double imputation would not be possible were it not for sin since the imputation of our sinfulness would not occur. In other words, we benefit from our sinfulness—a “genuine” part of us—being united to Christ. Call it redemptive perichoresis, if you will.
Perhaps some of these ideas are speculative. Whatever the case in that regard, one thing is sure, God’s decree of the fall of man was a perfect decree. As such, there will be a day when His saints are given more perspicuity into that decision, and when they do, they will proclaim, “Oh, the depth of the riches and wisdom and knowledge of God! How unsearchable are His judgments and unfathomable His ways!” (Romans 11:33, LSB).