God and reality
As these philosophers debate their existence and the existence of reality, the conversation takes a religious turn, as the title of the work suggests. They indulge in lengthy proofs about the alleged existence of God, and they seem to converge on an understanding: God is described by the team of thinkers as whatever force is behind the reality of nature and the logical order of reason. The term is shown as a symbolic reference, because they cannot discuss much more about God without indulging speculation, which the philosophers avoid.
The symbolic discourse
Also, the very shape of their discourse is an insightful symbol. Hume could have written these thoughts in an essay, but instead, he writes from multiple points of view. This is a dual symbol: It symbolizes the need for discourse in philosophy, because other points of view bring out issues and points of contention that are sometimes invisible in just one person's point of view. Also, the shape of Hume's Dialogues proves that he is attempting a circumspect philosophy. He plays the Devil's Advocate against his own self as a symbolic nod to skepticism.
Reason and logic
The existence of reason is not easy to treat, but basically there is a system of syllogistic reasoning which can be used to deduce conclusions from premises. If the patterns of reason are obeyed without flaw, then an argument is reasonable or valid. If the premises of an argument are also true, then the conclusion of a valid syllogism can be trusted as "true." The problem with this philosophical practice in Hume's opinion seems to be that the thoughts behind argument are infinite, so that a person can deconstruct an argument much more easily than they can construct a valid truth.
The emergence of skepticism
By his treatment of reason, Hume arrives at the emergence of true skepticism. For a Hume-like skeptic, religious philosophy boils down to one question: Will the thinker tolerate religious belief? The answer that Philo arrives at seems to be the most Hume-like conclusion in the Dialogues. Philo decides that beliefs are intolerable because they are easily dismantled with reason, and without substantial evidence to prove them correct, they must be rejected. His companions are offended by his harsh skepticism, but to Philo, it is the highest form of religious goodness. Skepticism is shown as a hyper-diligence to never say something is true that is not necessarily proven or provable. Hume's skepticism is similar to Logical Positivism in this regard.
The schism
The ending of the discourses is symbolic. The young student sides with his teacher Cleanthes. Demea, however, only deviated from Philo on the issue of religious belief. The schism between the student and teacher (a symbol for education and trust), and the two friends (Demea and Philo) is evidence that Hume has departed from the academy. Of course the young student follows Cleanthes; he still believes a myth about his teacher that his teacher has some sacred authority, but Philo and Demea know that Cleanthes does not have sacred, automatic authority. Philo is the winner of the debate, but even in the book, some people claim he is not the winner. The book's author seems historically to side with Philo's hyper-skeptical approach to religion.
