What does a 'change of raiment' signify in the Bible?

The term 'change of raiment' in Zechariah 3 represents the divine exchange of our sin and guilt for Christ's perfect righteousness. As Joshua stood in filth symbolizing his sin, God's command to remove this from him and clothe him anew illustrates the gospel truth that through Christ, our iniquities are removed, and we are dressed in His righteousness. This concept is foundational in Reformed theology, emphasizing that believers are not accepted based on their merits but solely because of Christ's merit imputed to them (2 Corinthians 5:21).