Definition and Symbolism:
Burning coals in the Bible often symbolize judgment, purification, and divine presence. They are frequently associated with God's holiness and the transformative power of His presence. The imagery of burning coals is used to convey both the destructive and purifying aspects of God's interaction with humanity.

Biblical References:

1. Judgment and Divine Wrath:
Burning coals are often depicted as instruments of God's judgment. In Psalm 18:12-13 , the psalmist describes a theophany where God’s presence is accompanied by "hailstones and coals of fire." This imagery underscores the power and majesty of God as He executes judgment upon His enemies. Similarly, in Ezekiel 10:2 , the prophet sees a vision where coals of fire are scattered over the city of Jerusalem, symbolizing impending judgment.

2. Purification and Atonement:
Burning coals also represent purification and atonement. In Isaiah 6:6-7 , a seraphim touches Isaiah's lips with a live coal from the altar, declaring, "Your iniquity is taken away, and your sin is atoned for." This act signifies the cleansing of Isaiah's sin, preparing him for prophetic ministry. The coal from the altar symbolizes the purifying fire of God that cleanses and sanctifies.

3. Divine Presence and Worship:
The presence of burning coals is associated with worship and the divine presence. In Leviticus 16:12-13 , the high priest is instructed to take a censer full of burning coals from the altar before the LORD and bring it inside the veil. The smoke from the incense on the coals creates a cloud that covers the mercy seat, signifying the presence of God in the Holy of Holies.

4. Metaphorical Usage:
Burning coals are used metaphorically to describe acts of kindness towards one's enemies. In Proverbs 25:21-22 , it is written, "If your enemy is hungry, give him food to eat; if he is thirsty, give him water to drink. For in so doing, you will heap burning coals on his head, and the LORD will reward you." This passage suggests that acts of kindness can lead to repentance and transformation in the heart of an adversary.

5. New Testament Reference:
The Apostle Paul echoes the metaphor from Proverbs in Romans 12:20 , encouraging believers to respond to evil with good, thereby "heaping burning coals" on the heads of their enemies. This reflects the transformative power of love and kindness, aligning with the teachings of Christ on loving one's enemies.

Theological Significance:
Burning coals in the Bible serve as a powerful symbol of God's holiness, justice, and mercy. They remind believers of the dual nature of God's fire—both as a consuming force against sin and as a purifying agent for those who seek His presence. The imagery of burning coals calls Christians to live lives marked by holiness, repentance, and love, reflecting the character of God in their interactions with others.