Divine motivation
(and Abrahamic motivation: dismembering the original blessing/promise)
א"ר יוחנן משום רבי יוסי בן זימרא אחר דבריו של שטן דכתיב (בראשית כא, ח) ויגדל הילד ויגמל וגו' אמר שטן לפני הקב"ה רבונו של עולם זקן זה חננתו למאה שנה פרי בטן מכל סעודה שעשה לא היה לו תור אחד או גוזל אחד להקריב לפניך אמר לו כלום עשה אלא בשביל בנו אם אני אומר לו זבח את בנך לפני מיד זובחו מיד והאלהים נסה את אברהם
Rabbi Yoḥanan said in the name of Rabbi Yosei ben Zimra: This means after the words [devarav] of Satan, as it is written: “And the child grew, and was weaned, and Abraham prepared a great feast on the day that Isaac was weaned” (Genesis 21:8). Satan said before the Holy One, Blessed be He: Master of the Universe, this old man, you favored him with a product of the womb, at one hundred years. From the entire feast that he prepared, did he not have one dove or one pigeon to sacrifice before You? God said to Satan: Did Abraham prepare the feast for any reason but for his son? If I say to him: Sacrifice your son before Me, he would immediately slaughter him. Immediately, after these matters, the verse states: “And God tried Abraham.”
Command vs. Request
A soldier cannot be ordered to win, only to fight
“And He said: Take, please [na], your son” (Genesis 22:2). Rabbi Shimon bar Abba says: na is nothing other than an expression of entreaty. The Gemara cites a parable of a flesh-and-blood king who confronted many wars. And he had one warrior, and he overcame his enemies. Over time, there was a fierce war confronting him. The king said to his warrior: I entreat you, stand firm for me in this war, so that others will not say: There is no substance in the first victories. Likewise, the Holy One, Blessed be He, also said to Abraham: I have tried you with several ordeals, and you have withstood them all. Now, stand firm in this ordeal for Me, so that others will not say: There is no substance in the first ordeals.
Two sons: Reminder of the last sacrifice
את בנך. ב' בנים יש לי. את יחידך. זה יחיד לאמו וזה יחיד לאמו. אשר אהבת. תרוייהו רחימנא להו. את יצחק.
וכל כך למה? כדי שלא תטרף דעתו עליו
When God said: “Your son,” Abraham said: I have two sons. When God said: “Your only,” Abraham said: This son is an only son to his mother, and that son is an only son to his mother. When God said: “Whom you love,” Abraham said: I love both of them. Then God said: “Isaac.” And why did God prolong His command to that extent? So that he would not go mad.
Satanic interference
Or: Abraham's internal monologue
קדמו שטן לדרך אמר לו (איוב ד, ב) הנסה דבר אליך תלאה הנה יסרת רבים וידים רפות תחזק כושל יקימון מליך כי עתה תבא אליך ותלא אמר לו (תהלים כו, יא) אני בתומי אלך
Satan preceded Abraham to the path that he took to bind his son and said to him: “If one ventures a word to you, will it be too much…you have instructed many, and you have strengthened the weak hands. Your words have upheld him that was falling…but now it comes upon you, and you are overcome” (Job 4:2–5). Abraham said to him in response: “And I will walk with my integrity” (Psalms 26:11).
Satan said to Abraham: “Is not your fear of God your foolishness?” (Job 4:6). Abraham said to him: “Remember, please, whoever perished, being innocent” (Job 4:7). Once Satan saw that Abraham was not heeding him, he said to him: “Now a word was secretly brought to me, and my ear received a whisper thereof” (Job 4:12). This is what I heard from behind the heavenly curtain [pargod], which demarcates between God and the ministering angels: The sheep is to be sacrificed as a burnt-offering, and Isaac is not to be sacrificed as a burnt-offering. Abraham said to him: this is the punishment of the liar, that even if he speaks the truth, others do not listen to him.
Consent of the victim
The Gemara cites an alternative explanation of the verse: “And it came to pass after these matters that God tried Abraham” (Genesis 22:1). Rabbi Levi says: This means after the statement of Ishmael to Isaac. Ishmael said to Isaac: I am greater than you in mitzvot, as you were circumcised at the age of eight days, and I at the age of thirteen years. Isaac said to Ishmael: And do you provoke me with one organ? If the Holy One, Blessed be He, were to say to me: Sacrifice yourself before Me, I would sacrifice myself. Immediately, God tried Abraham.
God and human sacrifice
And it is written: “And they have also built the high places of the Ba’al, to burn their sons in the fire for burnt offerings to Ba’al, which I did not command, and I did not speak, nor did it come into My heart” (Jeremiah 19:5).
אשר לא צויתי זה בנו של מישע מלך מואב שנאמר ויקח את בנו הבכור אשר ימלך תחתיו ויעלהו עלה ולא דברתי זה יפתח ולא עלתה על לבי זה יצחק בן אברהם
The Gemara interprets each phrase of this verse: “Which I did not command,” this is referring to the son of Mesha, king of Moab, as it is stated: “Then he took his firstborn son, who would reign after him, and he offered him as a burnt-offering” (II Kings 3:27). “And I did not speak,” this is referring to Jephthah, who sacrificed his daughter as an offering. “Nor did it come into my heart,” this is referring to Isaac, son of Abraham.
Fear and Trembling
Søren Kierkegaard (Johannes de Silentio)
I cannot make the movement of faith. I cannot shut my eyes and plunge confidently into the absurd; it is for me an impossibility, but I do not praise myself for that. I am convinced that God is love; for me this thought has a primal lyrical validity. When it is present to me, I am unspeakably happy; when it is absent, I long for it more vehemently than the lover for the object of his love. But I do not have faith; this courage I lack. …
But what did Abraham do? He arrived neither too early nor too late. He mounted the ass, he rode slowly down the road. During all this time he had faith, he had faith that God would not demand Isaac of him, and yet he was willing to sacrifice him if it was demanded. He had faith by virtue of the absurd, for human calculation was out of the question, and it certainly was absurd that God, who required it of him, should in the next moment rescind the requirement. He climbed the mountain, and even in the moment when the knife gleamed he had faith – that God would not require Isaac.
If someone deludes himself into thinking he may be moved to have faith by pondering the outcome of that story, he cheats himself and cheats God out of the first movement of faith – he wants to suck worldly wisdom out of the paradox.
The ethical as such is the universal, and as the universal it applies to everyone, which from another angle means that it applies at all times… The single individual, sensately and psychically qualified in immediacy, is the individual who has his purpose in the universal, and it is his ethical task continually to express himself in this, to annul his singularity in order to become the universal… Faith is namely this paradox that the single individual is higher than the universal – yet, please note, in such a way that the movement repeats itself, so that after having been in the universal he as the single individual isolates himself as higher than the universal. If this is not faith, then Abraham is lost, then faith has never existed in the world precisely because it has always existed. For if the ethical – that is, social morality – is the highest and if there is in a person no residual incommensurability in some way such that this commensurability is not evil (i.e., the single individual, who is to be expressed in the universal), then no categories are needed other than what Greek philosophy had or what can be deduced from them by consistent thought.
Faith is precisely the paradox that the single individual as the single individual is higher than the universal, is justified before it, not as inferior to it but as superior… now by means of the universal becomes the single individual who as the single individual is superior… This position cannot be mediated, for all mediation takes place only by virtue of the universal; it is and remains for all eternity a paradox, impervious to thought… The story of Abraham contains just such a teleological suspension of the ethical.
Source summary:
Taanit: For this story to have the right meaning, God must intend not to let Abraham kill Isaac.
Kierkegaard: For this story to have the right meaning, Abraham must know that God intends not to let him kill Isaac and he must be prepared to kill Isaac anyway.
Sanhedrin: We literally just said that.