Anselm based his theory of satisfactory atonement on Isaiah 53:11. KJV, which was later than Anselm, may perhaps not wholly mislead us. 'He shall see the travail of his soul and be satisfied.' I believe that Anselm read that as if the Father saw the the travail of the soul of the Son, and was satisfied. He then introduced the concept of honor. He did so from medieval jurisprudence. A king or lord of a manor, holding a court and calling his slaves to account, may not let any offense go undischarged. A fine may be imposed to end the matter. Any one may pay the fine who is able and willing. The honor of God, namely that every rational creature should obey his word, was offended by the disobedience of Adam, in which all men were involved. The infinitely worthy Second Person of the Trinity freely offered himself as a sacrifice to appease the offense. God first approved of the plan and then saw it put into effect and was satisfied. In Cur Deus Homo, which means Why Did God Become Man, Anselm deliberately put his Bible in the shelf and the Church fathers also. He wanted to appeal to pagans by reason alone. He did so without Bible verses, as he himself admits, but that is not to say he was not thinking of one, although we must needs guess which one. It is, however, unlikely that he made his proposal without any Biblical foundation at all. How could he? How could you or I? When, however, I look up the Isaiah verse in the Vulgate, the Latin Bible that Anselm was reading, it seems, to my little knowledge, to say, in effect that "Jesus who died shall be satisfied," as the hymn sings it, and not God the Father, and it also uses the verb saturabitur rather than satisfacere. So my theory is pretty shaky but I have not the heart to give it up entirely.

God being satisfied, according to Anselm himself, enabled him to be compassionate to man, which he was not able to be before. Since there is a good bunch of space left to write this, I might as well ask here whether the reader is satisfied with such a God! John Calvin does not seem to have been entirely happy. He admits that the sacrifice of Christ satisfied both the righteousness and the wrath of God, but vehemently rejects the idea that the satisfaction made God love us. Is Calvin simply overwhelmed by it that God so loved the world that he gave his only begotten son, that he allows the clear logic of Anselm to be swamped by the lovingness of God? I found this a memorable part of Calvin's Institutes of the Christian Religion, his great work.

Anselm's satisfaction theory of the atonement is developed in his book, Cur Deus Homo, and, as presented, is not "based on the Bible" like we might expect. Instead, Anselm relies heavily on logic, and largely avoids citing Scripture to make his case.

However, he is forced to rely on it in a few places, and he also tangentially mentions it in others. For example, he assumes the existence of God, and accepts the historicity of the Fall of Man as described in Genesis 3. While arguing that sin makes mankind a debtor to God, he mentions several texts (I'm quoting the NABRE here):

Colossians 2:14
obliterating the bond against us, with its legal claims, which was opposed to us, he also removed it from our midst, nailing it to the cross

John 8:34
Jesus answered them, “Amen, amen, I say to you, everyone who commits sin is a slave of sin.

Matthew 6:12
and forgive us our debts, as we forgive our debtors

Elsewhere, he argues that the God-man (Jesus) had to die voluntarily, and in support of this he cites a few more:

Isaiah 53:7
Though harshly treated, he submitted and did not open his mouth; Like a lamb led to slaughter or a sheep silent before shearers, he did not open his mouth.

John 10:18
No one takes it from me, but I lay it down on my own. I have power to lay it down, and power to take it up again.

For a few other examples, he cites Psalm 51 ("I was born in guilt, in sin my mother conceived me") to demonstrate the sinfulness of man, and uses language reminiscent of Deuteronomy 32:35 ("Vengeance is mine and recompense") to argue for God's superiority to man.

There are several more passages referenced by Anselm, but they are best explained in the context of his entire argument. A summary of that argument, along with additional Scripture references, follows.

As mentioned above, Anselm's purpose in Cur Deus Homo is to provide a rational argument, presupposing as little as possible and not relying on proof texts:

We have made it our aim to discover by reason alone whether [Christ's] coming was essential for the salvation of mankind. (1.20)

Thus, in order to provide a reasonably comprehensive answer the question, it will be necessary to outline Anselm's argument, briefly discussing its logic, and citing the biblical passages that he references along the way.

Anselm presents his ideas through a conversation between himself and an interlocutor named Boso. Anselm and Boso do not typically cite their sources when quoting from the Bible, and the wording they use doesn't always match modern translations. Below, the Bible quotes are all directly from the text of Cur Deus Homo, not a "standard" translation of the Bible, but the links point to the NABRE.

Anselm's argument takes the following form:

• Human sin dishonours God in such a way that repayment is required
• It is unfitting for God to forgive sin without punishment or satisfaction
• Humanity cannot make the required satisfaction
• God has a purpose for humanity that it is necessary for him to complete
• A God-man must be born with the power, obligation, and will to make the satisfaction
• The death of the God-man outweighs all sins

Human sin dishonours God and makes mankind his debtor

Anselm defines sin as "nothing else than not to render to God his due" (1.11). Anselm summarizes the consequences of sin:

Therefore, everyone who sins is under an obligation to repay to God the honour which he has violently taken from him, and this is the satisfaction which every sinner is obliged to give to God. (1.11)

Commentators call this understanding "feudal in origin" (xviii), and Anselm provides only indirect biblical basis. First, Boso, cites Colossians 2:14 ("bond of the decree") and John 8:34 ("slave of sin") as evidence that man is not a slave to the devil, but a slave to God's decree, and, by extension, to God himself (1.7). Later, in 1.19, Boso and Anselm interact over the implications of "forgive us our debts" in the Lord's Prayer (Matthew 6:12). In neither case does Anselm attempt to refute Boso, and in 1.20, he too adopts the word "bondslave" to describe man's relationship to God.

God cannot forgive sin without punishment or satisfaction

In 1.12, Anselm argues that God cannot simply overlook this debt that mankind owes him: it would be against his nature to do so. In such a case, sin would "slip by unregulated." Anselm says that "everyone knows" that righteousness is rewarded by God (cf. Deuteronomy 5:33), and on this basis argues if sin is neither paid for nor punished, it is not subject to any law (1.12). Furthermore, he says, "nothing is more intolerable" than sin, and therefore, "nothing [...] is more unjust to tolerate than the most intolerable thing" (1.13).

In challenge, Boso refers to the language of Matthew 6:12 ("forgive us our debts"), and wonders why man must simply forgive without repayment, but God cannot. Anselm responds:

There is no contradiction in this, because God is giving us the teaching in order that we should not presume to do something which belongs to God alone. For it belongs to no one to take vengeance, except to him who is Lord of all.

Here Anselm reflects the language of Deuteronomy 32:35 ("Vengeance is mine and recompense"), which is repeated in the New Testament in Romans 12:19 and Hebrews 10:30. (1.19)

Humanity cannot make the required satisfaction

Anselm next addresses the issue of man's attempts to repay God. Good works cannot repay the debt, because God created man "out of nothing" and is his Master, and a slave's obedience to his master is expected:

In obedience, when truth is told, what are you giving God that you do not owe him, seeing that it is your obligation to give him, at his command, all that you are and all that you have and all that you are capable of? (1.20)

Boso appeals to Galatians 5:6 ("faith which operates through love") and Ezekiel 18:27 ("if the wicked man turns from his wickedness and does what is right"), that faith is the means of obliterating wicked acts, but Anselm reminds him of the assumptions made so far in the argument: that, so far, Christ and the Christian faith do not exist.

Anselm argues that if given the choice between disobeying God, and allowing the destruction of the universe and everything in it, that the former option is still a sin: and that this gives us an idea of how bad sin is in God's eyes. (1.21)

He also refers to the "insult" that man gave God in the Garden of Eden (Genesis 3), when he "allowed himself to be conquered" by the devil through "persuasion alone," and thereby acted "contrary to the will and honour of God." In order to repay God for this insult, man must now do the opposite: being weak and mortal, he must "conquer the devil through the difficulty of death, and in so doing to sin in no way." But there's a problem: man is "born in sin" (cf. Psalm 51) and cannot accomplish this. (1.22) God recognizes man's incapacity, but since it is self-inflicted, his punishment should be increased, not reduced. (1.24)

It is necessary that God brings to completion his purpose for humanity.

Next, Anselm turns to the necessity of God completing his purpose for mankind. He argues that God's purpose for mankind includes filling heaven with a predetermined number of angels and men. The salvation of men, he says, does not depend on the Fall of angels, and there will be more elect men than fallen angels. He interacts with objections based on the "angels of God" reading found in the Septuagint of Deuteronomy 32:8 ("determined the limits of the peoples according to the number of the angels of God"), and argues that men can be considered "angels of God" in the same way that Judas was called a "devil" in John 6:70. (1.18)

But Anselm doesn't use explicit biblical support to defend what he sees as the overarching purpose of mankind:

Rational nature was created righteous to the end that it might be made happy by rejoicing in the highest good, that is, in God. Man, being rational by nature, was created righteous to the end that, through rejoicing in God, he might be blessedly happy. (2.1)

When man fell, this purpose was apparently thwarted, leaving God with two options: either dispose of his creation, or "complete what he has begun." Anselm argues that it is "totally foreign to [God] to allow any rational type of creature to perish utterly," and therefore, God must finish what he started with respect to mankind. (2.4)

A God-man must be born with the power, obligation, and will to make the satisfaction

The problem, Anselm summarizes, is that no one is capable of paying the debt except God, and only mankind has the obligation to pay it. Thus, a God-man is logically necessary to pay this debt.

Anselm argues that the only one who can pay the debt is "someone who would make a payment to God greater than everything that exists apart from God," who thus, logically, "must himself be superior to everything that exists apart from God." (2.6) At the same time, the God-man must be of the same race as Adam, because otherwise he is under no obligation to pay the debt. (2.8) To deal with objections based on Psalm 51 ("conceived in sin") and Romans 5:12 ("all have sinned"), which teach that all mankind is inherently sinful, he appeals to the "cleanness" of his virgin mother, which was made possible by his sacrifice. (2.16)

Simultaneously, the God-man must be willing to make the sacrifice. Anselm cites Isaiah 53:7 ("He was made a sacrifice, because he willed it") and John 10:18 ("power to lay down his life and take it up again") to argue that Jesus did in fact sacrifice himself voluntarily (2.17), and contends that other passages, like Philippians 2:8–9 and Matthew 26:39, do not contradict this understanding (1.9).

The death of the God-man outweighs all sins.

Finally, the satisfaction is achieved by the death of the God-man. Anselm argues that the God-man's life is worth more than all sins, and that thus his death outweighs them all. (2.14) Against the challenge that the sin of killing the God-man cannot be outweighed, Anselm responds by citing 1 Corinthians 2:8 ("if they had known it, they would not have crucified the Lord of glory"), arguing that the killers' lack of knowledge rendered the sin less severe, and thus it too was outweighed by the God-man's death. (2.15)

Citations, including all book/chapter numbers for Cur Deus Homo, refer to Anselm of Canterbury: The Major Works (Oxford World's Classics).

Book/chapter numbers can also be used in reference to public domain translations, such as this one, though there may be translation differences.