How do we know God is just in justifying the ungodly?

God's ability to justify the ungodly hinges on the vital truth that Christ was made sin for us. 2 Corinthians 5:21 states, 'For He hath made Him to be sin for us, who knew no sin; that we might be made the righteousness of God in Him.' This profound transaction demonstrates how God has maintained His justice while providing a means for sinners to be declared righteous. By laying our sins upon Christ, God allows for true justice to be fulfilled while also extending grace to those who believe.