Why do Christians rejoice in God's mercy?

God's mercy is a source of great joy for Christians, as it signifies the removal of sin and the bestowal of righteousness. In Isaiah 61:10, the church rejoices because they are covered with garments of salvation and the robe of righteousness, symbolizing the complete forgiveness of sins and acceptance before God. This joy is not merely conditional but is rooted in the assurance that through Christ's work, believers are forever reconciled to God, receiving the hope and comfort that comes with God's unending grace.