I've assembled quotations from three of Karl Barth's books to explain his robust Doctrine of Adam: The Church Dogmatics Vol. IV.1 §60, Christ and Adam: Man and Humanity in Romans 5, and The Epistle to the Romans (Romans II). I've assembled ten statements on Adam to summarized the following quotations from Barth's works.

#1. There are two biblical passages that explicitly refer to Adam: Genesis 2-3 and Romans 5:12-21 (1 Corinthians 15:22,24 may also be considered.)

#2. These passages contain elements of the Saga literary genre that makes scientific paleontology impossible to derive from them, or for polygenism to be excluded, or for specific information about a historical-Adam to be derived from these biblical texts.

#3. Adam has a twofold interpretation: an individual man and a general title for all individuals, such one meaning always includes the other.

#4. Adam is more than a metonymy, he is a first among equals, such that he represent the rebellion of the first man that all men likewise have joined.

#5. The fallen state of Adam (man) is not a poison that was passed on to Adam's children or a sexually transmitted disease, but a rebellion that Adam initiated, that all who were around and part of Adam, regardless of physical descent had joined in upon.

#6. This fallen state is the consequence of no single historical act: it is the unavoidable pre-supposition of all human history.

#7. There never was a golden age. There is no point in looking back to one. The first man was immediately the first sinner.

#8. Adam is like the rainbow in relation to Jesus like the sun. Adam is only a reflection of Jesus. The rainbow has no independent existence of the Sun. The rainbow cannot stand against the sun. It does not balance it, and the same is of all people in Adam and the one person of Jesus.

#9. Barth and Calvin teach that the corruption of all mankind in the person of Adam alone did not proceed from ordinary generation, but from the appointment of God.

#10. No one has to be Adam. We are so freely and on our own responsibility. Although the guilt of Adam is like ours, it is just as little our excuse as our guilt is his.

In Christ and Adam, Barth explains how Adam is at once an individual and all of humanity. Adam is an individual and all individuals are Adam.

What Rom 5:12-21 is specially concerned to make clear is that man as we know him, man in Adam who sins and dies, has his life so ordered that he is both a distinct individual and, at the same time, the responsible representative of humanity and of all other men. In the same way there are no other responsible representatives of humanity than individual men. We are what Adam was and so are all our fellow men. And the one Adam is what we and all men are. Man is at once an individual and only an individual, and, at the same time, without in any way losing his individuality, he is the responsible representative of all men. He is always for himself and always for all men.

Barth, Karl. Christ and Adam; Man and Humanity in Romans 5. Trans. T. A. Smail. New York: Collier, 1957. 112-3. Print.

Another quotation from Barth's Christ and Adam, expands the idea that we are all Adam. No one in particular person is Adam, because all individuals take up Adam's insurgence. No one is innocent, and no one may say they are wrongly punished for what some other man has done, yet at the same time, we are all one in Adam, and the very first man at his initial step missed the mark and gave into the lordship of sin.

The parallel must first be seen be seen as such. In both cases there is the one, and in both, the many, all men. Here, in Adam, is the one, who by what he is and does and undergoes, inaugurates, represents, and reveals what the many, all men who come after him, will also have to be and do and undergo. But here, in Adam, are also the many, all men, not one of them the less guilty or the less penalized because he is not himself the one, but each rather finding himself completely in what the one is and does and undergoes, and recognizing himself only too clearly in him. There, in Christ, is, for the first time in the true sense, the One who stands, as such, for all the others. He also is the Inaugurator, Representative, and Revealer of what through Him and with Him the many, all men shall also be, do, and receive. And there, also for the first time in the true sense, are the many, all men, not one of them less righteous or less blessed because he is not the One, but each rather finding and recognizing himself again in what this One who takes his place is, and does, and has received. As in the existence of the one, here in Adam, the result for the many, all men, is the lordship of sin, and, with it, the destiny of death; so again, in the existence of the One, there in Christ, the result for all men is the lordship of grace exercised in the divine righteous decision and promise of eternal life.

Barth, Karl. Christ and Adam; Man and Humanity in Romans 5. Trans. T. A. Smail. New York: Collier, 1957. 42-3. Print.

In Karl Barth's infamous commentary, The Epistle to the Romans (sometimes called "Romans II"), the essential point is made that there is no one single isolated historical act of a so-called Historical Adam that is to blame for the lordship of sin over humankind, because this acts is a corporate act of all men, and one we all take up willingly in the beginning of every individual's life. The very first man took up this insurgence, yet all people take up this insurgence, because it is our anthropology.

Adam is the 'old' subject, the EGO of the man of this world. This EGO is fallen. It has appropriated to itself what is God's, in order that it may live in its own glory. This fallen state is the consequence of no single historical act: it is the unavoidable pre-supposition of all human history, and, in the last analysis, proceeds from the secret of divine displeasure and divine rejection. Directly related to this 'Fall' is the condemnation unto death, pronounced upon all men; whereby the naturalness and creatureliness, the inadequacy, tribulation, and corruption, of men, as men of this world, constitute alike their curse and their destiny (Rom 5:18). For (Rom 5:19)—by one man's disobedience the many were made sinners. The action of Adam does not merely throw light upon his own individual character; rather, it defines individuality itself, all individuals,—the many. For those who have eyes to see, the many are discovered and exposed as sinners. There is no man, who as a man and as he really is, is not—in Adam. As such, therefore, the old and fallen subject is set under sentence of death, under negation, under the wrath of God.—Such, then, is the old world by which we are continually generated.

Barth, Karl. Trans. Edwyn Clement Hoskyns. The Epistle to the Romans. London: Oxford UP, H. Milford, 1968. 181. Print.

The Epistle to the Romans and Christ and Adam represent bookends to Barth's theology, but the centerpiece is always The Church Dogmatics. And Barth may not know apart from what he wrote in the Church Dogmatics! At the end of the Church Dogmatics Vol. IV. §60, contains the following excellent quotations on Adam that repeat the content of the previous quotes and add (what should be obvious) that these sparse biblical references to Adam are not grounds for any scientific paleontology. The biblical accounts contain various degrees of saga (the literary genre) that makes a historical paleonotogy impossible to derive from Gen 2-3, Rom 5:12-21 and 1 Cor 15:22,45. A point that needs to be repeated frequently is that if Adam is presented biblically as a singular individual as a patriarch of all men, this does not mandate or necessity that a historical man, named Adam as such, that his life was recorded in scripture as straight forward literal history that is absent of any form of saga, metaphor, allegory, or interpretation. It is anachronistic to impose scientific precision upon the text, such that anyone may use the scientific method to determine the historicity of this so-called 'Historical Adam'.

The Bible gives to this history and to all men in this sense the general title of Adam. Adam is mentioned relatively seldom both in the Old Testament and the New. There are only two passages which treat of him explicitly: Gen 2-3 and Rom 5:12-21 (to which we might add 1 Cor 15:22,45). The meaning of Adam is simply man, and as the bearer of this name which denotes the being and essence of all other men, Adam appears in the Genesis story as the man who owes his existence directly to the creative will and Word and act of God without any human intervention, the man who is to that extent the first man.

We could see and attest the coming into being of heaven and earth and especially the coming into being of Adam and his corresponding individual existence? It is not history but only saga which can tell us that he came into being in this way and existed as the one who came into being this way—the first man. We miss the unprecedented and incomparable thing which the Genesis passages tell us of the coming into being and existence of Adam if we try to read and understand it as history, relating it either favorably or unfavorably to scientific paleontology, or to what we know know with some historical certainty concerning the oldest and most primitive forms of human life. The saga as a form of historical narration is a genre apart. And within this genre biblical saga is a special instance which cannot be compared with others but has to be seen and understood in and for itself. [...]

It is the name of Adam the transgressor which God gives to world-history as a whole. The name of Adam sums up this history as the history of the mankind which God has given up, given up to its pride on account of its pride. It sums up the meaning or meaninglessness of this history, and—this is the Word and judgment of God on it, this is the explanation of its staggering monotony, this is the reason why there can never be any progress—it continually corresponds to his history. It is continually like it. With innumerable variations it constantly repeats it. It constantly re-enacts the little scene in the garden of Eden. There never was a golden age. There is no point in looking back to one. The first man was immediately the first sinner.

Barth, Karl. Trans. G. W. Bromiley. Church Dogmatics: IV.1 The Doctrine of Reconciliation. Ed. G. W. Bromiley and T. F. Torrance. Vol. 22. London: T & T Clark, 2009. [507-08]. Print. Study Edition..

In this next quotation from The Church Dogmatics, Adam is introduced as the "first among equals" interpretation, concluding that Adam is not an metonymy for us all in abstract of individual. Adam is the first man, who first lead the rebellion we all have participated in, but he is us all, yet at the same time, the very first man who first committed this treasonous act of insurgence established what man is. It's not a poison that was passed on to Adam's children or a sexually transmitted disease, but a rebellion that he initiated, that all who were around and part of Adam, regardless of physical descent had joined in upon. When a man initiates an insurgences, often his children participate, but most participates of an insurgency are not physical descendants. Almost always, accomplices in crimes are genetically unrelated.

Who is Adam? The greatest unknown who is the first parent of the race? There can be no doubt that this is how the biblical tradition intended that he should be seen and understood. But it is interested in him as such only for what he did. A sinner specially burdened with his act? But compared with what the Old Testament tells us of others, and even of holy men, his offence was obviously so slight and trivial that in view of his particular fault we should hesitate to describe him even as the primus inter pares (first among equals). Certainly there is no reason why a special accusation should be brought against him and his act. He simply did in the insignificant form of the beginner that which all men have done after him, that which is in a more or less serious and flagrant form our own transgression. He was in a trivial form what we all are, a man of sin. But he was so as the beginner, and therefore as primus inter pares (first among equals). This does not mean that he has bequeathed it to us as his heirs so that we have to be as he was. He has not poisoned us or passed on a disease. What we do after him is not done according to an example which irresistibly overthrows us, or in an imitation of his act which is ordained for all his successors. No one has to be Adam. We are so freely and on our own responsibility. Although the guilt of Adam is like ours, it is just as little our excuse as our guilt is his. We and he are reached by the same Word and judgment of God in the same direct way. The only difference is that what we all are and do he was and did at the very gateway of history, and therefore he was reached first by the Word and judgement of God in a way which is typical for all his successors. That is Adam as seen and understood in the biblical tradition, the man who sinned at once, the man who was at once proud man, the man who stands at the gateway as the representative of all who follow, the one whom all his successors do in fact resemble (in the fact that they all sin at once as well).

Barth, Karl. Trans. G. W. Bromiley. Church Dogmatics: IV.1 The Doctrine of Reconciliation. Ed. G. W. Bromiley and T. F. Torrance. Vol. 22. London: T & T Clark, 2009. [509-10]. Print. Study Edition.

In the next quotation from Church Dogmatics Vol. IV. §60, is the most important corrective; Adam and Jesus Christ are not peers, or two or a kind, or equals in anyway. Adam is 'a type of him who is to come' who is Jesus Christ. All people have gone astray in Adam and redemption comes from the one man Jesus Christ. Therefore, all people are in Adam and all redemption is in Jesus Christ; the one for the many and the many for the one is Christ and Adam.

We ought to speak of the parallel between Adam and Christ. But at the very least we ought to speak of the parallel between Christ and Adam. For there can be no doubt that for Paul, Jesus Christ takes the first place as the original, and Adam the second place as "the figure of him that was to come" (Rom 5:14), the prophetic type of Jesus Christ. He knew Jesus Christ first and then Adam. But that means that in Adam, in his existence and act and function, in his relationship to the race which derived from him, he saw again, as it were, the negative side of Jesus Christ. In the unrighteous man at the head of the old race he saw again the righteous man at the head of the new. And even the term parallel calls for some explanation. It is not autonomously that the line of Adam and the many who are concluded with him in disobedience runs close to that of Jesus Christ in whose obedience God has willed to have and has had mercy on many and indeed on all. We have only to note how the two are contrasted in Rom 5:15-17 to see that although they can be compared in form they cannot be compared in substance. The former is like the rainbow in relation to the sun. It is only a reflection of it. It has no independent existence. It cannot stand against it. It does not balance it. When weighted in the scales it is only like a feather. That is the relationship between the offence of men in the person and act of one and the free gift of righteousness and life which comes with the judgement of God in the persona and act of this other. That is the relationship between the determination of all men and mankind and the history of man on the one hand and their determination on the other.

Barth, Karl. Trans. G. W. Bromiley. Church Dogmatics: IV.1 The Doctrine of Reconciliation. Ed. G. W. Bromiley and T. F. Torrance. Vol. 22. London: T & T Clark, 2009. 513. Print. Study Edition.

Barth quotes John Calvin's Commentary of John (3:6) that I've provided in context to demonstrated how Barth is in development out of the Reformed Tradition. The essential 'sentence' is that it is not by "ordinary generation" that the corruption of mankind subsists but it exists by the direct "appointment of God".

But here it may be objected, that since the soul is not begotten by human generation, we are not born of the flesh, as to the chief part of our nature. This led many persons to imagine that not only our bodies, but our souls also, descend to us from our parents; for they thought it absurd that original sin, which has its peculiar habitation in the soul, should be conveyed from one man to all his posterity, unless all our souls proceeded from his soul as their source. And certainly, at first sight, the words of Christ appear to convey the idea, that we are flesh, because we are born of flesh. I answer, so far as relates to the words of Christ, they mean nothing else than that we are all carnal when we are born; and that as we come into this world mortal men, our nature relishes nothing but what is flesh. He simply distinguishes here between nature and the supernatural gift; for the corruption of all mankind in the person of Adam alone did not proceed from generation, but from the appointment of God, who in one man had adorned us all, and who has in him also deprived us of his gifts. Instead of saying, therefore, that each of us draws vice and corruption from his parents, it would be more correct to say that we are all alike corrupted in Adam alone, because immediately after his revolt God took away from human nature what He had bestowed upon it.

http://www.ccel.org/ccel/calvin/calcom34.ix.i.html#Bible:John.3.6

(Header Image Source: Hieronymus Bosch (circa 1450–1516) [Public domain], via Wikimedia Commons)