Exodus 32:21 in the King James Version of the Bible reads: "And Moses said unto Aaron, What did this people unto thee, that thou hast brought so great a sin upon them?" This verse occurs in the narrative of the Israelites' grave sin of idolatry. While Moses was on Mount Sinai receiving the Ten Commandments from God, the people grew impatient and asked Aaron to make them a god to worship. Aaron complied, creating a golden calf that the people then worshiped.

Moses' question to Aaron in Exodus 32:21 reveals his shock and disappointment at the people's actions, as well as his concern for Aaron's role in the sin. The verse serves as a pivotal moment in the story, highlighting the severity of the Israelites' transgression and the spiritual and moral leadership of Moses and Aaron.

One of the central themes in this verse is the concept of sin and its consequences. The Israelites' construction and worship of the golden calf was a direct violation of their covenant with God, as well as a rejection of His authority and commandments. The gravity of the sin is emphasized in Moses' question to Aaron, as he seeks to understand how such a great sin could have been committed. This theme underscores the importance of obedience and faithfulness to God, as well as the need for accountability and repentance in the face of sin.

The verse also highlights the role of leadership and responsibility in the context of faith and community. Moses, as the appointed leader and intermediary between God and the Israelites, holds Aaron accountable for his role in the people's sin. His question to Aaron reflects his concern for the spiritual well-being of the community and his commitment to upholding God's commandments. This theme emphasizes the importance of moral and spiritual leadership, as well as the need for individuals to be accountable for their actions within the community of faith.

Symbolically, the golden calf represents the Israelites' inclination towards false gods and material idols. Throughout the Bible, the golden calf is used as a symbol of idolatry and the worship of false gods, representing humanity's tendency to stray from the true path of faith and obedience to God. The construction and worship of the golden calf also serve as a symbol of the Israelites' lack of trust and patience in waiting for God's guidance and provision. The consequences of the sin, including the breaking of the tablets of the law, the destruction of the calf, and the punishment of the idolaters, serve as a powerful symbol of the destructive nature of sin and the need for repentance and reconciliation with God.

In conclusion, Exodus 32:21 presents a powerful commentary on the themes of sin, leadership, and idolatry within the context of the Israelites' transgression with the golden calf. The verse underscores the severity of the sin and the need for accountability and repentance within the community of faith. It also serves as a symbolic reminder of the consequences of straying from the path of obedience and faithfulness to God. As such, Exodus 32:21 continues to offer valuable lessons and insights for individuals and communities of faith, emphasizing the importance of moral and spiritual leadership, accountability, and the rejection of false idols in favor of true and faithful worship of God.