The second problema asks, "Is there an absolute duty to God?" Johannes again defines the ethical as universal, which he in turns associates with the divine and with duty to God. Every duty is a duty to God insofar as God is the divine is the universal. For instance, it may be my duty to love my neighbor, and this duty, as an ethical duty, is a duty to the universal and thus to God. However, Johannes notes, we have no direct relation to God through these duties, but only an indirect relation according to which our duties may be traced back to God.

Hegel suggests that the outer, or exteriority, is higher than the inner, as what is outer is publicly expressed, is universal. If this is so, Johannes suggests, Hegel is wrong to speak about faith and about Abraham as he does. Faith is that paradox that the inner is higher than the outer, that the single individual can relate absolutely to the absolute as a single individual. Though not invalidated, the ethical becomes relative, and the single individual's absolute duty is to God. This duty to God, as absolute, cannot be mediated and thus cannot be expressed in the universal: if it were expressible, it would not be faith but spiritual trial. The knight of faith cannot make himself understandable, not even to another knight of faith.

Johannes cites Luke 14:26 as teaching an absolute duty to God: "If any one comes to me and does not hate his own father and mother and wife and children and brothers and sisters, yes, and even his own life, he cannot be my disciple." The word "hate" is often softened in translation to "love less" or "count as nothing." Such a translation renders something terrible and vigorous into overblown nonsense about being less good to other people. In demanding absolute love, God does not ask that we stop loving our family. Abraham loves Isaac dearly, but the ethical expression of what he does at Mount Moriah is hatred.

Existing as the single individual is often considered easy, and for this reason the universal is identified as a more laudable goal. However, Johannes suggests, if one lives properly under one's own surveillance, if one speaks with "fear and trembling," one knows that existing as the single individual is the most terrible and the greatest existence there is. The knight of faith must know and value the universal, but must also know what it's like to be higher than the universal, to be alone and misunderstood. Abraham did not seem heroic to others; he seemed mad. In the end, however, the knight of faith can address God in the second person singular ("thou"), while the tragic hero can only use the third person.

The tragic hero's lot is not as difficult as the knight of faith's. The tragic hero can act, and then is finished, and can rest, knowing that he has successfully achieved the universal. The knight of faith is constantly being tested, and faced with the possibility of returning to the universal. The knight of faith is distinguished by having the passion to remain always in absolute isolation. Johannes concludes that either there is an absolute duty to God as he has explained it, or there isn't and Abraham is lost and Luke 14:26 is overblown nonsense.

The mainstream position in Kierkegaard's day (and in our own) that there is no absolute duty to God is most convincingly put forward by Kant. He argues that we can only be autonomous and responsible for our moral choices if we act not in obedience to some external law, but in accordance with laws that we freely will ourselves. I cannot rationally justify my actions by saying "God told me to," but only by saying that I acted of my own free will in accordance with a law that I should wish were universally applied. Kant, followed by Hegel, argues that all moral laws should be universal: for instance, it is never right to lie, regardless of the circumstances. Hence, Hegel identifies the ethical with the universal.

Johannes moves against this position in suggesting that there is an absolute duty to God; that is, that there are cases--for instance, Abraham's--where one should act in opposition to all universal ethical principles.

A Hegelian might identify God with the Absolute Mind, that is, as the embodiment of the universal truth. To attain this truth, we must suppress our individuality and participate instead in the universal. There is no private relation to God because we must forgo our privacy in order to come into contact with God: as a result, we can only speak of God in the third person. Johannes seizes on this point in suggesting that the knight of faith can speak to God in the second person singular. Most languages, including English until a few centuries ago, have two different forms of "you." The singular ("thou") is more intimate and friendly. The plural ("you") is used to speak either to more than one person, or to speak with formal distance. Johannes suggests that the knight of faith has an intimate relation to God.

Johannes argues that the knight of faith acts in total isolation from everyone else. His relation to God is a private one, and cannot be justified by an appeal to the universal. Faith, Johannes argues, is precisely that paradox that the single individual is higher than the universal. Though it is noble for the single individual to aspire to the universal, God may call for actions that cannot be justified in the universal.

In acting as a knight of faith, Johannes suggests, one is constantly being tested. One is being asked to act against the ethical, to abandon entirely one's own judgment as to what is right, and to act in unquestioning obedience to God. Either Abraham was obeying God or he was a murderer, and it took great faith for him never to question himself or to question God, never to doubt that he might in fact be a murderer. The temptation, then, is to comply not with faith, but with the universal, to do what one knows is right. This temptation is far stronger than any temptation to pursue personal, unethical pleasures. The temptation in that case is to do what one knows is wrong; the temptation for the knight of faith is to do what he knows is right. He is constantly being tested, because the option to follow his moral judgment is always available to him.

This section of the text contains the only mention of "fear and trembling," an allusion to Philippians 2:12-13. The passage urges Christians to "continue to work out your salvation with fear and trembling, for it is God who works in you to will and to act according to his good purpose." This "fear and trembling" seems appropriate for the constant testing that a knight of faith undergoes. The knight of faith must recognize that it is God who works in him, and that he cannot question or doubt. He must necessarily face this test with fear and trembling since he is going against the ethical and he knows that the option to retreat into the ethical is always open to him.

This "fear and trembling" is central enough to the message of the book that Kierkegaard chose it as a title. No doubt, the choice of title was partly inspired by Kierkegaard's poetic flair, but it also suggests a spirit of Christianity that he feels is lost in his age. In an age when Hegel's universal is esteemed, in which the public, the outer, the open is valued, we lose a sense of the privacy and the anxiety with which one enters into a relationship with God. Johannes suggests that either this privacy exists and Hegel is wrong, or Abraham is a murderer. With typical irony, he leaves it to the reader to decide which is correct.