What does the Bible mean when it calls God a consuming fire?

from the old testament

• The phrase, “consuming fire,” refers to a fire that “eats” or “devours” all that is around it. A forest fire is an example of a consuming fire, where nothing seems to be able to stop it. It goes where it wants and “consumes” whatever it touches. The phrase is used metaphorically to refer to God’s wrath against sin. For example, when God descended on Mount Sinai to meet with His recently freed people, He commanded that only Moses was allowed to approach the mountain (Exodus 24:2). Anyone else, including animals, would be instantly killed if they came close because God was holy and would not allow any unholy person or thing to come near (Exodus 19:13–25). Any that did would be consumed by His wrath.
• In Deuteronomy 4:23–24, the consuming fire is related to God’s jealousy. The people of Israel were not to worship other gods because God deserves all worship. Being jealous means that He consumes those who disregarded His warning to keep His exclusivity.
• Deuteronomy 9:3 also refers to the Lord as a consuming fire. God would serve as a consuming fire to destroy Israel’s enemies. Like a wildfire, He would remove all the sinful people living in the land.
• Isaiah prophesied against Israel (Isaiah 29:6), Assyria (Isaiah 30:27, 30), and “sinners in Zion” (Isaiah 33:14). In each case, God’s judgment is described as a consuming fire. Again, like a fire ravages all the trees in a forest, the judging fire of God consumes all sinners.
• The Old Testament also refers to fire and God as purifying or judgement (Genesis 19:24; Exodus 3; Exodus 9:23–24; Exodus 13:22). In each case, “fire” and, specifically, “consuming fire,” refers to God’s response to sin. He is a merciful God, but when He unleashes His wrath against sin and sinners, nothing stands in its way. His judging wrath is a consuming fire.

from the new testament

• The New Testament mentions “consuming fire” in Hebrews 12:29, recalling how Mount Sinai shook when God appeared. It points forward to Jesus’s return, when heaven and earth will be shaken in judgment. Yet believers are assured that God’s kingdom is unshakable. In light of this, we are called to worship with reverence and awe. God’s consuming fire motivates us to live in obedience, knowing final judgment is coming.

implications for today

God is a holy God. That means that He cannot allow sin to exist unchecked. However, God is also merciful. Though He promises to one day cast all who reject Jesus into His eternal hell of non-stop, consuming fire (Mark 9:47–48), He sent His Son, so you can escape His wrath (Romans 5:9) and have eternal life (John 3:16).

If you are currently an unbeliever, then God’s wrath is hanging over you right now like a consuming fire (John 3:36b). However, whoever repents from sin and trusts in His Son, Jesus, will never have to face that wrath. That is because Jesus already consumed His wrath in full on the cross when He died. Turn and repent before it is too late!

If you are currently a believer, then knowing about God’s consuming fire has two implications. First, it reminds you just how holy God is. Though Jesus paid for your sin, that does not mean you can continue to sin (Romans 6:1–2). Instead, you are to pursue holiness to be like your God and to continue to repent and ask for forgiveness when you fail (1 John 1:9). The second implication is that, though you are saved from God’s wrath, there are still many who are not, and it is likely that you know people who are currently under His wrath. Don’t turn your back on them! Just like God was merciful to you, be merciful to them and let them know just how great—and fearful—God is so that they might also flee the fire to come (Matthew 3:7)!