Two Mountains, Two Mediators, One God
Few passages in the New Testament draw the contrast between the two covenants more vividly than Hebrews 12:18-29, and few passages have more to say about how we perceive God. The writer sets up a deliberate and dramatic comparison. On one side stands Mount Sinai — a scene of blazing fire, darkness, gloom, a tempest, the blast of a trumpet, and a voice so overwhelming that the people begged it to stop (Hebrews 12:18-19, Exodus 19:16-19). Even Moses, the mediator of that covenant, said, "I am terrified and trembling" (Hebrews 12:21). The law that descended from that mountain came with a boundary — touch the mountain and die (Exodus 19:12). The entire encounter communicated one overwhelming message: God is holy, and you are not, and the distance between you is absolute.
On the other side stands the New Mount Zion, the city of the living God, the heavenly Jerusalem — and the contrast could not be more complete. Here there is no fire that must not be touched, no trumpet that causes terror, no mediator trembling at the voice. Instead, the writer describes a festive gathering: the city of the living God, innumerable angels in joyful assembly, the church of the firstborn (new creations) enrolled in heaven, and Jesus, the mediator of a new covenant, whose sprinkled blood speaks a better word than the blood of Abel (Hebrews 12:22-24). Abel's blood cried out for justice. Christ's blood speaks peace. The mountain has changed. The mediator has changed. The access has changed entirely. Hebrews 4:16 speaks of boldness in Christ to approach a throne of grace and mercy.
This is where the danger of a poorly formed theology becomes painfully practical — because many believers have unconsciously assembled a portrait of God drawn more from Sinai than from Zion. They read Exodus 19 and 20, hear the thunder and see the smoke, and carry that image forward as the defining picture of who God is in His disposition toward humanity. But this misreads what Sinai was communicating. God was not revealing His permanent posture toward people — He was revealing His holiness and the unbridgeable gap of sin, made explicit through the Law. The terror of Sinai was not God's character on full display; it was the ministry of condemnation doing exactly what Paul said it does — producing death where sin meets holiness without a mediator who can bear the weight (2 Corinthians 3:7-9).
John addresses the character question directly. He writes that Jesus is the Greek ἱλασμός (hilasmos) for our sins — the propitiation, the atoning satisfaction — and not for ours only but for the whole world (1 John 2:2). Propitiation is a precise word. It means the righteous requirement has been fully met, the wrath absorbed, the separation ended. John then draws a conclusion that reframes everything: God is love (1 John 4:8). Not God was love before He got angry, not God will be love once we perform well enough — God is, in His essential nature, love. And the demonstration of that love is not Sinai. It is the cross. Paul says it plainly in Ephesians 2:4-7 — God, being rich in mercy, because of the great love with which He loved us, made us alive together with Christ, so that in the coming ages He might show the immeasurable riches of His kindness toward us. The cross is not God punishing humanity — it is God absorbing the punishment Himself in order to lavish kindness on humanity across eternity. That is the character behind both mountains.
God did not change between the Testaments. He cannot — He is the same yesterday, today, and forever (Hebrews 13:8). What changed is the covenant, and with it, the mode of His relating. Under the Old, the mediator was a servant who trembled. Under the New, the mediator is the Son who says come to me (Matthew 11:28). Under the Old, the mountain could not be touched. Under the New, the veil has been torn and the way into the Holy of Holies stands open (Hebrews 10:19-20). To construct a portrait of God from Sinai alone — wrathful, distant, thundering, lethal to the touch — and then carry that portrait into the New Testament is to misread both. It is to miss what propitiation accomplished. It is to stand at the foot of the wrong mountain.
Yet the writer of Hebrews does not allow us to grow careless at this point, and this is where the passage reaches its fullest tension. After all the beauty of Mount Zion, the writer warns: do not refuse Him who is speaking. For if those who refused the one who warned them on earth did not escape, how much less will we escape if we reject the One who warns from heaven (Hebrews 12:25)? And then the closing declaration — "our God is a consuming fire" (Hebrews 12:29). The fire has not gone out. But what the fire now consumes is different. At Sinai, the fire kept people away. In the New Covenant, the fire of the Holy Spirit is a baptism (Matthew 3:11). The same consuming holiness that once established an uncrossable boundary now dwells within the believer as the agent of transformation. God is shaking everything that can be shaken — every element of a sinful nature, every system, every false foundation, every religious structure built on human effort — so that what remains is the kingdom that cannot be shaken (Hebrews 12:27-28). The fire is not punishing the redeemed; it is refining them, burning away what is temporary so that what is eternal remains.
This is the invitation of the new covenant: not to approach a mountain of terror, but to receive and enter a kingdom of grace — and to worship with reverence and awe, not because we are afraid of being struck down, but because we understand what it cost to bring us near and who our God is. The consuming fire is real. But for those in Christ, it is the fire of a Father's love that will not stop until every impurity is gone and every child is fully formed into the image of the Son.