The question of why God allowed the death of His only Son, Jesus Christ, for the redemption of humanity's sins while seemingly allowing the continued existence of His adversary, Satan, is a profound theological conundrum that many believers encounter on their faith journey. To address this, it is necessary to take a closer look at biblical scripture, which provides key insights into God's nature, His purposes for humanity, and the cosmic battle between good and evil.

In Christian theology, the crucifixion of Jesus Christ is central to God's plan for humanity's salvation. John 3:16 succinctly expresses this: "For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life." The sacrifice of Jesus is seen as the ultimate expression of God's love and mercy. It serves multiple purposes. Primarily, it is an atonement for sin.

According to Romans 3:23-25, all humans have sinned and fall short of the glory of God. Jesus's death is viewed as the atonement for these sins, offering reconciliation between humanity and God. Moreover, Jesus's sacrifice fulfils numerous Old Testament prophecies about the Messiah who would suffer and die for the sins of humanity (Isaiah 53). By rising from the dead, Jesus conquered death and provided a way for eternal life (1 Corinthians 15:54-57). This sacrificial act is not just about paying the price for sin but also about demonstrating God's profound love and justice. It addresses the problem of sin and the separation it causes between humanity and God. Romans 5:8 proclaims, "But God demonstrates his own love for us in this: While we were still sinners, Christ died for us." This act of sacrifice bridges the gap between divine holiness and human sinfulness.

Yet, despite this monumental act of love, Satan, often referred to as "the adversary" or "the accuser", continues to exist and operate in the world. Christian theology posits that Satan's continued existence serves several purposes within God's sovereign plan. God created humans with free will, allowing them to choose between good and evil. Satan's presence provides the context for moral testing and the exercise of free will. This choice is vital for genuine love and obedience to God. Without the option to choose otherwise, love and obedience would be devoid of true meaning.

The existence of evil and Satan ultimately highlights the contrast between God's goodness and the pervasiveness of sin. Through the struggle against evil, God's righteousness and justice are more fully revealed. The presence of evil provides a backdrop against which the goodness of God shines more brilliantly. This cosmic struggle underscores the reality of free will and the nature of moral struggle inherent in the human experience.

Christian eschatology teaches that there will be a final judgement where Satan and all evil will be decisively defeated (Revelation 20:10). This event is part of God's sovereign design, demonstrating His ultimate justice and the restoration of creation. The final judgement ensures that justice prevails, with Satan and all evil being eradicated. This paves the way for the restoration of creation, where righteousness dwells (2 Peter 3:13).

2 Peter 3:9 provides insight into God's patience and long-term plan: "The Lord is not slow in keeping his promise, as some understand slowness. Instead he is patient with you, not wanting anyone to perish, but everyone to come to repentance." God's delay in destroying Satan is an expression of His desire for all people to have the opportunity to repent and turn to Him. This divine forbearance underscores God's desire for all to be saved and come to a knowledge of the truth (1 Timothy 2:4).

Faith in Jesus Christ transforms lives and empowers believers to resist evil. Ephesians 6:10-18 describes the "armour of God" that Christians are called to wear to stand against the devil's schemes. This metaphor illustrates that, while Satan exists, God equips believers with the spiritual resources to overcome his influence. Christians are equipped with the Holy Spirit, who empowers them to live victoriously amidst spiritual warfare (Romans 8:11). The reality of eternal life through Christ and the certainty of God's ultimate justice compel believers to share the gospel and demonstrate God's love in tangible ways, fulfilling the Great Commission (Matthew 28:18-20).

The crucifixion of Jesus and the continued existence of Satan both serve to highlight different aspects of God's character and His plans for humanity. Jesus's sacrifice is the pinnacle of God's love, offering redemption and eternal life. Meanwhile, Satan's presence underscores the reality of free will, the nature of moral struggle, and the ultimate triumph of good over evil. In Christian theology, God's patience and sovereignty are paramount, ensuring that His purposes are fulfilled in ways that bring about the greatest good and reveal His glory.

To experience this revelation is therefore down to us, resulting from the choices we make, the behaviour we adopt, and the pathways in life we choose to follow. Living in the light of these theological truths, believers are encouraged to pursue holiness, resist evil, and spread the message of the gospel. This understanding deepens our comprehension of God's character and encourages us to live faithfully and purposefully, knowing that our struggles are part of a larger, divine narrative that culminates in the restoration of all things.