Is the God of the Old Testament and New Testament the same?
Yes — the same God of grace and justice is revealed across both Testaments. Grace fills the Old Testament — God is ‘merciful and gracious, slow to anger, and abounding in mercy’ (Psalm 103:8) — and justice fills the New, where Jesus warns us to fear the One who can destroy both soul and body (Matthew 10:28). His justice and mercy are not at war; they meet at the cross, where God judged sin in Christ and freely pardons sinners.
In the second century, a man named Marcion proposed that the God of the Old Testament was a different — and inferior — God from the Father of Jesus. The Church rejected this firmly, and Marcionism was condemned as heresy. But the underlying instinct — the Old Testament God seems harsh, the New Testament God seems kind — is still very much alive. Modern critics put the case sharply. Richard Dawkins calls the God of the Old Testament “the most unpleasant character in all fiction… a petty, unjust, unforgiving control-freak; a vindictive, bloodthirsty ethnic cleanser… capriciously malevolent bully.”
The argument is that the New Testament God of grace cannot be the same as the angry God of the Old Testament. But He is. The Bible presents one God, progressively revealed across redemptive history — and that one God is both gracious and just throughout both Testaments.
Grace appears on the first pages of Scripture. After the fall (Genesis 3), God does not wipe humanity out; He pursues them. He clothes Adam and Eve with garments of skin (Genesis 3:21) and promises a Saviour from the woman's seed who will crush the serpent's head (Genesis 3:15). The flood judges a corrupt world, but Noah finds grace in the eyes of the LORD (Genesis 6:8). God calls Abraham out of paganism and promises that in him “all the families of the earth shall be blessed” (Genesis 12:3).
The pattern continues. God bears with Israel's rebellion through the wilderness, the judges, the monarchy, and the exile, recalling them through prophets they did not deserve. He commands Hosea to marry an unfaithful woman, Gomer, and to keep loving her even after she abandons him — a living picture of God's covenant love for an unfaithful Israel. He sends Jonah to preach to Nineveh, the brutal capital of Assyria; and Jonah runs from the assignment precisely because he suspects God will show grace and spare them (Jonah 4:2). The Psalmist sings the same truth as praise: “The LORD is merciful and gracious, slow to anger, and abounding in mercy… He has not dealt with us according to our sins, nor punished us according to our iniquities” (Psalm 103:8, 10). If grace were the New Testament God's distinctive, the Old Testament writers never received the memo.
The pattern runs the other direction too. The God of the New Testament is no less just than the God of the Old Testament. In Acts 5, Ananias and Sapphira lie to the Holy Spirit about a property gift, and both are struck dead on the spot — and “great fear came upon all the church” (Acts 5:11). Hebrews warns that “it is a fearful thing to fall into the hands of the living God” (Hebrews 10:31). The book of Revelation closes the Bible with images of divine wrath poured out — bowls, plagues, the lake of fire — language as severe as anything in the prophets.
Jesus Himself spoke about hell more frequently, and more vividly, than anyone else in the New Testament. Outer darkness. Weeping and gnashing of teeth. The worm that does not die. The fire that is not quenched. The same Jesus who said, “Come to Me, all you who labor and are heavy laden, and I will give you rest” (Matthew 11:28) told the unrepentant to fear “Him who is able to destroy both soul and body in hell” (Matthew 10:28). The grace of the New Testament is real, but it does not cancel the justice of the New Testament. Both stand in the same book, often on the lips of the same speaker.
So why do we feel the tension at all? Because grace and justice look like opposites — and in any system where one had to cancel the other, they would be. The cross is where the Bible refuses that trade.
At Calvary, the Father did not set aside His justice in order to forgive. He carried it out — on His own Son. The wrath that sin deserved fell in full; and in the same act, the grace that sinners could never earn was poured out freely. Justice was not suspended so that mercy could win. Justice and mercy met.
And it was one God who brought them together — the Father purposing it, the Son accomplishing it, the Spirit applying it to all who believe. This is why the Reformed tradition insists the cross was never God's plan B, a course-correction after a harsh beginning. It was the eternal counsel of the God who, from before the foundation of the world, meant to reveal His justice and His grace at a single point in history.