What does being justified mean in the Reformed context?

In Reformed theology, justification is the act of God declaring a sinner to be righteous on account of Christ's satisfaction of the law through His life and death. The sermon highlights that just as our sins were placed upon Christ, His perfect obedience and righteousness are credited to us. This means believers are viewed not as guilty but as fully justified before God, allowing them to stand without guilt. As 2 Corinthians 5:21 states, Christ was made sin for us so that we might become the righteousness of God in Him. This truth instills assurance and peace in believers that nothing they do can add to or diminish God's declaration of their righteousness.