Buckle up for a long and extraordinary passage of Barthian theological exegesis:

If God does not meet us in His jealous zeal and wrath—exactly as He meets Israel according to the witness of the Old Testament, exactly as He meets it later in the crucifixion of His own Son—then He does not meet us at all, and in spite of all our asseverations about divine love, man is in actual fact left to himself. That man is not abandoned in this way, that God is really gracious to him, is shown in the fact that God confronts him in holiness. It is in this way that God is present with him, taking over and conducting the cause which sinful man is impotent to conduct himself. It is in this way that God reconciles man to Himself. The fact that God does not permit Israel, the righteous, or the Church to perish means that He cannot allow them to go their own way, when they are and behave as if they were people who do not participate in this salvation and protection. The burning bush of Exodus 3:2 cannot be consumed. But the unconsumed bush must burn. This bush is Israel. And the flame which burns it but does not consume it is the God of Israel, the Holy God. When God spake: Let there be light, and there was light, and God saw that it was good, God separated the light from the darkness and the light He called day and the darkness night (Gen. 1:3f). This separation could only have been avoided if God had not spoken: Let there be light, and there had not been light, and God had not seen that the light was good. Because this is true and actual, it must also be true and actual: “And the light of Israel shall be for a fire, and his Holy One for a flame: and it shall burn and devour his thorns and his briers in one day; and shall consume the glory of his forest, and of his fruitful field, both soul and body: and they shall be as when a standard-bearer fainteth. And the rest of the trees of his forest shall be few, that a child may write them” (Is. 10:17f). And at this point how can we help thinking of Is. 6:1f where the prophet sees the Lord sitting on a throne high and lifted up, and his train filled the temple? Above it stood the seraphims, and one cried to another: “Holy, holy, holy, is the Lord of hosts: the whole earth is full of his glory. And the posts of the door moved at the voice of him that cried, and the house was filled with smoke.” Then the prophet exclaims (exactly like Peter in Lk. 5): “Woe is me! for I am undone; because I am a man of unclean lips, and I dwell in the midst of a people of unclean lips: for mine eyes have seen the King, the Lord of Hosts.” And accordingly there follows the terrible touching of his lips with a live coal from the altar, but also the explanation: “Lo, this hath touched thy lips; and thine iniquity is taken away, and thy sin purged.” Consider this point. It is not after, but in the manifestation of wrath and judgment that there comes the pardon, reconciliation, calling and commissioning of the prophet, in short, the grace, which was obviously from the very outset the secret meaning of this whole revelation of God’s holiness. In this sense we clearly have to understand the preaching of judgment to the people with which Isaiah is at once entrusted, and in fact the prophetic preaching of judgment generally, even when it is not completed and qualified by any specific prophecy of salvation. How can it be ignored as the immediate inevitable consequence of the revelation of holiness and the Law of holiness? It is where the name, the people, the city, the house of God is, that judgment must begin (Jer. 25:29; 1 Pet. 4:17). Binding Himself to Israel, God binds Israel to Himself, and binding Israel to Himself, He becomes to it the inextinguishable fire whose flame is nothing else but the flame of His love. Making Himself its God, He subjects it to His Law, His threats and His punishments in order to confer on it His blessings by this subjection. Separating it from among the peoples, in all the things in which its native way of life is the same as that of the heathen, He must deal with it just as He does with the ladder, and indeed incomparably more strictly. To this day [!!!] He must heap misfortunes upon Israel as compared with other peoples in order to accomplish supremely its separation, and therefore its promise, and therefore His own gracious election and turning to this people. The freedom of grace is revealed in the fact that it is always manifest in judgment. But it is the freedom of grace which is revealed in this way. If it is God who enters into fellowship with man, and if this happening spells grace and election, is it not inevitable that the opposition, indeed the consuming opposition, between God and sinful man should be made manifest? And conversely, if God did not make known His consuming opposition to sin, and therefore to sinful man, how could He really hold fellowship with man, seeing He can do so only on the basis of grace and election? To accept God’s grace necessarily means, therefore, to respect God’s holiness, and therefore to accept, heed and keep His laws, to fear His threats, to experience His wrath and to suffer His punishment. Otherwise acceptance of grace is indistinguishable from heathen quietism. But again, respect for God’s holiness, if it is not a vain heathen religion of fear, can only mean directly to accept God’s grace and thankfulness, to be contentedly replenished by it. “Wherefore we receiving a kingdom which cannot be moved, let us hold fast thankfulness, whereby we may serve God acceptably with reverence and godly fear. For our God is a consuming fire” (Heb. 12:28f). Again, if anywhere the unity of Old and New Testaments is visible, if anywhere we not only can but must speak of the Old Testament witness to Christ and of Christ as the fulfillment of the Old Testament, it is precisely in this connexion where the too fashionable exegesis of both Testaments has always tried to divorce Moses and Christ, the Law and the Gospel. For it is the witness of the Old Testament and its fulfilment that God made to be sin (2 Cor. 5:21) His own beloved Son in whom He was well pleased (Mk. 1:11), that He condemned sin in Him (Rom. 8:3), and that because He thus humbled Himself unto the death of the cross, He gave Him the name which is above every name (Phil. 2:9), and that in all this, He made His own business the sanctification of His people, the expiation of its sin, the embodiment of His will in the life of His people, thus giving this people the opportunity of receiving and accepting by faith the divine judgment, but also of finding in it the forgiveness of sins and the promise of eternal life and therefore of fleeing sin as surely as it cannot wish to flee from divine grace. “And for their sakes I sanctify myself, that they also might be sanctified through the truth” (Jn. 17:19). When we look at Jesus Christ we cannot fail to see how the apparently varied threads in the Old Testament witness of God all intertwine, His election and His wrath, His forgiveness of sins and His commandments, His graciousness and His holiness; and that according to the Old Testament witness the Lord who deals with Israel is the one God in all this diversity. Again, the Old Testament attests and affirms that Jesus Christ, in whom God turns to man while remaining completely true to Himself, discloses a life which in the Old Testament sense can be adequately described only by the appellation God. If God’s love is what is revealed to us in Jesus Christ, if Jesus Christ Himself is the revealed love of God, there is an end of the divorce between God’s grace and holiness, and there remains to us only the recognition and adoration of Him who is both gracious and holy: gracious as He is holy and holy as He is gracious.

— Karl Barth, CD II/ §30.1 (“The Grace and Holiness of God”), pp. 366–67. How often Barth’s most stunning passages, like this one, are drawn forth by sheer theological—better, pastoral!—frustration with one of his Liberal forebears: in this case, Albrecht Ritschl, who argued (speaking for many in his own day and in ours) that the concept of divine wrath is progressively eliminated over the course of the Bible, with the wrathful God of the Old Testament ultimately giving way to the loving and gracious God of the New. What bad news this would really be! This draws forth Barth’s purest and richest instincts as a preacher (the real inner secret, I am coming to think, of his “theological method”). The judgment of God, the holiness of God, are Gospel: because, as Barth says a few pages prior, “In Scripture we do not find the Law alongside the Gospel but in the Gospel” (p. 363). Thank God for His graciousness and holiness, His purifying judgment, His Law that kills us in order that His Spirit may make us fully alive.