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, no hearts of stone but hearts that are epistles of a living God who writes his laws there. Instead to old covenant boundaries and hostilities the writer describes a new one, 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 the boldness we have in Christ to approach this mountain, a throne of grace to receive grace and mercy as needed.
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).
For there is one God, and one mediator between God and people; a person, Christ Jesus, who gave himself as a ransom for all, the testimony at the proper time. (1 Timothy 2:5-6)
The danger of how we can perceive the two covenants and thus God is evident in this passage. Paul also addresses in Galatians what is true for the church today. The church can go back to the Law and develop unsound theology. An example today is tithing, where Malachi 3:10-12 is used in the new covenant to invoke the blessings of tithing where God opens the "windows of heaven" to pour out overwhelming earthly blessings and "rebuking" the devourer. Giving is taught in the New Testament but not tithing. Jesus completely over turns other previous precepts in the Old Testament through the beatitudes, saying love your enemies and pray for those who persecute you... The great are servants, not lords with authority over people thundering from a pulpit (Matthew 20:25). We can build a system of religion on authority, fear and judgement... all from the Old Testament. We can call our system holy because it is from the Bible. We can adhere to Sabbath days, tithing and offerings, festivals, even worship angels and can call mountains and places holy because they were in the Bible, or even where Jesus walked. And miss Jesus altogether.
Do not work for food that spoils, but for food that endures to eternal life, which the Son of Man will give you. For on him God the Father has placed his seal of approval (John 6:27)
This is what many people wanted in religion today, an earthly kingdom with earthly blessings, but Jesus said no this is not why I came. John writes that Jesus is the word of God and was a "propitiation for sin" 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 His purpose and promise between the Testaments (Hebrews 13:8). What changed is the covenants, and with it, the mode of relating. And really the new was God's original plan, see The Promised Eternal Covenant. Under the Old, the mediator was a servant who trembled. Under the New, the mediator is the Son who says "come to me all who are weary and heavy burdened and I will give you rest" (Matthew 11:28). Jesus is the mediator of a new covenant, an eternal high priest we have before God, one with better promises. 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. It is to make a offering on the altar when God has provided the sacrificial Lamb.
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 consumed animals and 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 God, of grace and truth — 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.