How can God be just and still declare sinners righteous?

The conundrum of God being just while declaring sinners righteous is resolved through the atoning work of Christ. 2 Corinthians 5:21 teaches that Christ was made sin for us, allowing God to be both just and the justifier of the one who has faith in Jesus. This profound mystery means that when God looks upon believers, He sees the righteousness of Christ instead of their sin. The perfect and complete sacrifice of Christ before God ensures that both justice and grace are fully satisfied, leading to our justification.