The phrase "fire from their mouths" is a vivid biblical image primarily associated with the prophetic and apocalyptic literature of the Bible. This imagery is most notably found in the Book of Revelation, which is rich with symbolic language and visions concerning the end times.

Revelation 11:5
In the Book of Revelation, the phrase is used in the context of the two witnesses, who are granted authority to prophesy during the tribulation period. Revelation 11:5 states: "If anyone wants to harm them, fire proceeds from their mouths and devours their enemies. This is how anyone who wants to harm them must die" . This passage suggests a divine protection over the witnesses, symbolizing the power and authority given to them by God. The fire represents judgment and the ability to defend themselves against opposition, emphasizing the seriousness of their mission and the divine backing they possess.

Symbolism and Interpretation
The imagery of fire proceeding from the mouths of the witnesses can be interpreted in several ways. It may symbolize the power of their prophetic words, which carry divine authority and can bring about judgment. In the biblical context, fire is often associated with God's presence, judgment, and purification (e.g., Exodus 3:2, Malachi 3:2-3). Thus, the fire from their mouths could represent the purifying and judging power of God's word spoken through His prophets.

Old Testament Parallels
The concept of fire as a divine instrument is not new to the New Testament. In the Old Testament, fire frequently appears as a symbol of God's presence and judgment. For instance, in 2 Kings 1:10-12, Elijah calls down fire from heaven to consume the soldiers sent by King Ahaziah. This event underscores the authority of God's prophets and the seriousness of opposing them.

Prophetic Authority
The two witnesses in Revelation are often seen as figures of great prophetic authority, akin to Moses and Elijah, who performed miracles and spoke God's truth to a rebellious people. The fire from their mouths serves as a testament to their divine commission and the power of God's word to enact His will on earth.

Theological Implications
From a theological perspective, the imagery of fire from their mouths highlights the theme of divine justice and the ultimate triumph of God's purposes. It serves as a reminder of the power of God's word and the certainty of His promises. The protection and authority given to the witnesses reflect God's sovereignty and His commitment to fulfill His redemptive plan.

In summary, "fire from their mouths" is a powerful biblical image that conveys the authority, protection, and judgment associated with God's prophetic messengers. It underscores the seriousness of their mission and the divine power that accompanies the proclamation of God's word.