I will comment on five quotes from this book that might cause someone to lose their faith in Jesus.
Quote No. 1. Christians resorted ever more systematically to a logic that treated the relative "Jewishness" of a teaching as the best test of its truth or falsity. "Jews" multiplied as negative types in Christian writing, and the living Jew (as opposed to the prophets of the past) became in the Christian theological imagination the enemy of the Christian. (location 1562)
The author is implying that Christianity caused anti-Semitism. The following quote from the The Origins of the Inquisition in Fifteenth-Century Spain by Benzion Netanyahu says that anti-Semitism caused Christianity:
Christian theology did not create or initiate the hatred of the Jews that saturates its teachings--it was, on the contrary, created and shaped by it. The instinct of hatred was simply hardened into a doctrine that constituted the foundation of the new religious edifice. (page 22)
Quote No. 2. Despite Augustine's retrospective enthusiasms, these philosophical ideas are not obviously compatible with Judaism or Christianity. (location 1626)
The "philosophical ideas" referred to are a metaphysical idea and a theological idea. The metaphysical idea is that God is an infinite and immutable being and therefore would have no motive for creating the universe of finite beings. This is indeed a mystery because the only thing that could motivate God to do anything is self-love. Finite beings exist because God loved Himself as giving. But God could just as well love Himself without giving. Hence, the existence of finite beings is a mystery. To his credit, the author uses the word obviously to modify compatible.
The theological idea is that God would not inspire Western prophets and Eastern mystics to say our purpose is life is to serve Him in this world in order to be with Him in the world to come. There are two kinds of knowledge: faith and reason. In reason, we know something is true because we can see the truth of it. In faith, we know something is true because God is telling us. Faith is both a decision and a gift from God. Christians are summoning people to believe in God and are giving their reasons. But it is not a demand. It is wrong to criticize the judgment of someone who does not have the gift of faith.
Quote No. 3. If Jesus suffered as a man, could he also be a god? (location 1635)
We can comprehend what Jesus suffered, but we can't define or explicate what human suffering is. A human being is an indefinability that becomes conscious of its own existence. Humans are embodied spirits. One can expresses this in metaphysical terms by saying the human soul is spiritual. Since other human beings exist, humans are finite beings and a composition of two metaphysical principles: essence and existence. An infinite being is a pure act of existence without a limiting essence. The infinite being is called God in the Western religions.
I understand the Christian doctrine of the Incarnation as being subordinate to the doctrine of the Trinity. When human beings communicate with one another the communication is imperfect. This can't be true of an infinite being. God communicates with us in three different ways: by creating us and keeping us in existence (the Father), by answering our prayers (the Holy Spirit), by giving us Jesus (the Son).
Quote No. 4. The synagogue 'began to be burnt by the judgment of God.' Behind this judgment stood the entire church. The bishop and his monks were but the instruments of God's justice, their violence a proclamation of his sovereignty, for insofar as the synagogue represented an exceptional space outside the law of Christ, its existence diminished that sovereignty. (location 2023)
The quotation is from Saint Ambrose, the Bishop of Milan, who was criticizing Emperor Theodosius for defending the legal rights of Jewish people in the Mesopotamian city of Callinicum in 388 AD. On page 316, there is a reference to the excommunication of Theodosius by Saint Ambrose, but this was for the massacre at Thessalonica in 390, another Macedonian city.
Theodosius ordered the massacre in a fit of anger when a riot over a false arrest caused the death of an officer in the Roman army. Theodosius's Gothic troops surrounded an amphitheater, filled because of a circus, and killed a predetermined number of the hapless spectators. In addition to the hooligans rounded up and executed by the local authorities after the riot, seven thousand were killed in the amphitheater, it was said. After performing public penance for eight months, Theodosius humbly went to Ambrose for the sacrament of Holy Communion.
To summarize, the Catholic Church caused the Emperor to repent by threatening eternal damnation and used force and violence to suppress Judaism. The author refers to "God's justice," but there is no other kind of justice. The alternative to believing in God's justice is thinking that human beings have rights because they are human beings. An example of someone who thinks this is Nick Machiavelli who was the first to justify immoral acts for "reasons of state." It is quotes like this that gave the devil the nickname "Old Nick":
From this it may be concluded that men should either be caressed or exterminated, because they can avenge light injuries, but not severe ones. The damage done to a man should be such that there is no fear of vengeance. (Niccolò Machiavelli, The Prince and Other Writings (Barnes & Noble Classics) by Allan H. Gilbert, New York: Hendricks House, 1964, p.99)
Quote No. 5. "In short, I do not believe that the history of thought I have attempted to sketch in these pages determined why Germany moved from anti-Semitism to genocide....But I do believe the Holocaust was inconceivable and unexplainable without that deep history of thought." (location 7893)
Referring to the horrors of the French Revolution, the author asks in italics, "Could the triumph of reason unleash even greater barbarism that what had come before?" (location 6481). The answer of course is yes, as the author knows very well. But the author does not blame the ideas that produced the French Revolution. The author thinks that the triumph of reason over faith was a good thing. My guess is that the author admires Machiavelli and Darwin, who said human beings evolved from animals, but does not admire Saint Ambrose.