The ambigram
An ambigram is a text that reads the same if viewed upside-down. This method of calligraphy is employed by the Illuminati when they brand their victims. This is a meaningful symbol as it points to the reversed morality of the book, and emphasizes how the objective truth of the plot is exposed, in spite of the inverted intentions of religious men and terrorists alike. From the positive and negative, the matters of fact in the plot are immune to their portrayal.
The ambigram also reflects the ambiguity raised in terms of defining the titular Angels and Demons. It is never clear that in the war between science and religion, which is good and which is bad. The ambigram on the cover page depicts this.
Antimatter
This is a wonderful symbol, although many of the scientific details about its inclusion may indicate a mistaken understanding about the actual physics of antimatter. But, insofar as antimatter is portrayed in the novel, it is a meaningful symbol.
Antimatter represents the grey area between theology and physics, where both systems involve the study of unseen truths. This is thematically related to the book, because the plot involves learning the truth about things that are not readily apparent. It also serves as the face of science which can be lethal and yet resourceful creating debates its potential.
The Catholic church as a symbol/motif
The Catholic church represents a particular belief system, while also incurring many specific implications about the plot through its constituent parts. That is, the church is both a symbol and a system for symbols. The church as a symbol represents the position of religion and man's religious systems in the course of the plot. It allows for a meaningful discussion about belief and intent and corruption and potential within man's search for God.
As a system, the church, specifically the power play toward being Pope, shows man's utilization of religion for his own purposes. This is a cynical, skeptical approach to religion, but it does allow for a meaningful interaction with religious skepticism, which is obviously a core concern for the narrative.
The Illuminati
The Illuminati serves as a system of characters in the plot narrative, as well as being a symbol in the narrative. The society provides a method for discussions in the narrative about religion and corruption, religious terrorism, belief versus skepticism, and many other thematic discussions.
Illuminati literally means "the enlightened," and hence the learned ones. But, the term can also be understood as "belonging to Lucifer," thus creating ambiguity about people in Science and their motivations with respect to religion.
The elements
When the Illuminati kills the Preferiti, they brand them with the words, Fire, Air, Water and Earth. Their inculsion of the elements into their murder has meaningful implications; namely it points out that the forces that have indicted the religious men are the forces of the observable universe. This shows religion to be flawed at its very nature. Perhaps the most powerful indictment against religious systems is the physical world that they seek to explain.
The branding is also ironical as people from church were said to murder scientists and branding them upon altars. Thus, the whole ritual of branding a bishop with an element is a sort of revenge from religion.
The elements also represent a rebellion from Science towards religion because these elements were considered as components of nature by learned men as opposed to Church. The inclusion of these elements as the main theme in some of the most important artifacts of Church is like a blow in the face of Church.
