Rationalists fail to appreciate the role of religion in disseminating philosophy. These doctrines become the bedrock of a civilization. While there are many similarities, there are also significant dissensions between the teachings of different religions.
Philosophy is the foundation on which all our knowledge is built. It has several major branches. Metaphysics deals with the nature of reality. How we know this reality is the domain of epistemology. Deciding what is right and wrong is the sphere of ethics. How we live together under a system of laws is the field of politics.
These subjects are closely interrelated. Our ideas about the nature of reality determine what we believe to be true, which in turn determines our notions of right and wrong. The laws governing our interactions with each other are the result of our system of ethics.
Human beings are social and depend upon cooperation. This is possible only on the basis of trust. At an individual level, we must know someone well enough to determine if trust is warranted. Sociologists have theorized that a person can know about 150 people to this degree. During primitive times, this was also the typical size of a clan, which was basically a group of related families.
To trust people beyond this group, we need a system of ethics. Religions serve this purpose. At a fundamental level, there are two ways to accomplish this. The Abrahamic religions expect their ethics to be enforced through fear of a god. To make this system work, there can be only one god, and he needs to be kept as unknowable as possible.
Dharmic religions, on the other hand, teach that our sense of right and wrong is innate. It is the result of our cooperative nature. Collaboration works best under harmony. This is fostered by teaching the law of consequences, also known as karma.
In modern times, most nations accommodate people of many different religions. Often, the underlying ethical systems of these religions are quite antipodal. To overcome this problem, laws are made without regard to religion, to the extent possible. There is an implicit agreement that everyone will abide by these secular laws, even when they do not align with their religion. Further, these laws are expected to not favor one religion over another.
This is somewhat self-contradictory and impractical. Some differences cannot be resolved through compromise. There is no middle ground between supremacy and equality. Civics classes in school don’t help much. No one gets their sense of right and wrong by studying ethics. By the time we are ten years old, our morality is pretty much set in stone. And it is based on the religion followed by those who influenced us most during this formative period.
Religion is the basis of civilization. There can be no civilization without religion. It is what teaches us our philosophy of life. Religion is to philosophy what engineering is to science.