How do we know that justification is only through Christ?

In the sermon, it is emphasized that the core question of how God can be just and yet justify the ungodly finds its answer in the atoning work of Jesus Christ. As John 2 illustrates with the water to wine miracle, Christ transforms believers by His grace, making them righteous before God. 2 Corinthians 5:21 affirms 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 underscores that our justification is not based on our works or inherent righteousness but through Christ’s sacrificial act that reconciles us to God.