How do we know Christ's work is vital for salvation?

The necessity of Christ’s work for salvation is established in Scripture, where it's indicated that He is the only mediator capable of reconciling sinners with God. His death satisfied divine justice, as 2 Corinthians 5:21 affirms, stating that 'He made Him to be sin for us, who knew no sin, that we might be made the righteousness of God in Him.' This imputation of Christ's righteousness to those who believe is paramount; it establishes that salvation is not based on human effort but on Christ’s perfect obedience and sacrificial death. If his work were inadequate, we would remain in our sins, as the glory of God’s grace is inherently tied to the efficacy of Christ’s atoning sacrifice.