How do we know that our iniquity is pardoned according to the Bible?

In Isaiah 40:2, it is declared that God's people have received comfort because their iniquity is pardoned. This pardon is not merely a declaration of leniency; it is secured through the sacrificial work of Jesus Christ, who took on our sins and bore the wrath of God on our behalf. 2 Corinthians 5:21 further explains how Christ was made sin for us, enabling us to receive God's righteousness. Therefore, our forgiveness is rooted in Christ's accomplished work, assuring us that all debts of sin have been fully paid.