In biblical literature, the imagery of "filthy garments" is a powerful symbol representing sin, impurity, and the need for divine cleansing and redemption. This metaphor is most prominently featured in the Old Testament, particularly in the prophetic book of Zechariah.

Zechariah 3:1-5
The most direct reference to filthy garments is found in Zechariah 3:1-5. In this passage, the prophet Zechariah receives a vision of Joshua the high priest standing before the Angel of the LORD, with Satan accusing him. Joshua is described as wearing filthy garments, symbolizing the sin and impurity of the people he represents. The Angel of the LORD commands those standing before Him to remove Joshua's filthy garments, saying, "See, I have removed your iniquity, and I will clothe you with splendid robes" (Zechariah 3:4). This act signifies God's forgiveness and the cleansing of sin, as well as the restoration of righteousness.

Symbolism and Interpretation
The filthy garments in this vision symbolize the moral and spiritual defilement of Israel, particularly the priesthood, which had been compromised by sin and unfaithfulness. The removal of these garments and the subsequent clothing with clean, splendid robes represent God's grace and the transformative power of His forgiveness. This imagery underscores the necessity of divine intervention for purification and the restoration of a right relationship with God.

Theological Implications
From a theological perspective, the concept of filthy garments highlights the human condition of sinfulness and the inability to achieve righteousness through one's own efforts. It emphasizes the need for God's grace and mercy to cleanse and redeem. The vision of Joshua's cleansing prefigures the ultimate redemption through Jesus Christ, who, according to Christian belief, provides the means for humanity's purification and reconciliation with God.

Related Biblical Themes
The theme of garments as symbols of righteousness or sin is prevalent throughout the Bible. In Isaiah 64:6, the prophet laments that "all our righteous acts are like filthy rags" , further illustrating the inadequacy of human righteousness apart from God. In the New Testament, the Apostle Paul speaks of believers being clothed with Christ's righteousness (Galatians 3:27), reinforcing the idea that true righteousness comes from God alone.

Practical Application
For believers, the imagery of filthy garments serves as a reminder of the need for continual repentance and reliance on God's grace for spiritual cleansing. It encourages a life of holiness and dedication to God, recognizing that true purity and righteousness are gifts from Him. The transformation from filthy garments to splendid robes is a call to live in the new identity provided through faith in Christ, reflecting His righteousness in daily life.