A straightforward explanation as to why God allows sin in the world, and the overarching reason behind all His actions, is for one ultimate purpose: His glory. However, it’s important to clarify that God’s glory isn’t dependent on sin; rather, His response to sin showcases His glorious attributes.

It was God’s desire to put His full glory on display, which includes His compassion, mercy, grace, forgiveness, kindness, justice, wrath and holiness. These attributes of God are not necessitated by sin, but through His interaction with a fallen world, these aspects of His character are vividly revealed.

Unless sin existed, aspects such as God’s mercy, grace, forgiveness, compassion, and lovingkindness might not be as evident. Sin serves as a backdrop that highlights the beauty of God’s holiness and righteousness. By understanding what is unholy, we come to appreciate the holiness of God. The existence of evil allows us to recognize good, and the presence of impurity underscores the value of purity.

While God allows the existence of sin, it is still within the bounds of His sovereign will and purpose. This allowance is not an endorsement of sin but a part of the greater narrative of redemption and transformation.

Every action of God is meant to achieve His glory. He exhibits His glory not just before creatures on earth, but also to angels in heaven:

Ephesians 3:10 (NKJV)

to the intent that now the manifold wisdom of God might be made known by the church to the principalities and powers in the heavenly places,

In conclusion, the existence of sin in the world serves to highlight, by contrast, the magnificent attributes of God. It also points us toward the ultimate redemption and transformation that is at the heart of God’s plan. This understanding offers hope and assurance in the meaningfulness of God’s actions in a world touched by sin.