The term naturalism is usually contrasted with supernaturalism to emphasize that things and occurrences in the world can be understood in terms of the laws of nature, without invoking supernatural entities as do most traditional religions. Many philosophers, both ancient and modern, have subscribed to a naturalist philosophy, as do a great many professional scientists. Most naturalists are either atheists, that is, they deny the existence of any God; or they are pantheists, that is they picture a God who pervades all of Nature. Much of the inanimate world, and even many features of living creatures, including human beings, may be adequately explained in terms of the physical entities and principles discovered by science. Traditional religions speak about the human condition as something special, with characteristics that are too unique and subtle to be reduced to the basic ingredients of matter. They insist that there are human attributes such as thought and feeling, formulations of right and wrong, the sense of justice and the quest for truth, the capacity to reason and to create poetry, that we may bracket into the notion of the human spirit. And the human spirit, say most religions, transcends matter and energy, atoms and photons. It is not within the scope of science to analyze it to its ultimate material components.
Until the rise of Darwinian evolution in the latter half of the nineteenth century, even biologists kept religion and God as separate from science. However, the theory of evolution brought in two elements that blatantly contradicted traditional religious belief systems. First, the theory of evolution explains that Man did not appear fully constituted on the planet; rather, he emerged ever so slowly from lower forms of life. Secondl, the variety of organisms in the world resulted from chance factors which instigate the emergence of different plants and animals. The success of Darwinism led some biologists to imagine that some day science would replace all of the symbols and artifacts of religion.
The goal of science is to explore every aspect of the natural world. Science strives to account for all of the richness and variety in the phenomenal world in terms of fundamental entities, immutable laws, and universal principles. Naturalism is characterized by complete faith in the potential and total success of the methodology of science in efforts to understand every aspect of the phenomenal.
Naturalism is characterized by a confidence in science's potential to understand such aspects of the phenomenal world as are important to our existence; or at least that through the methods of science, we can understand them better than through any other mode. This confidence arises from the proven successes of the scientific methodology during the past four centuries.
To some, the extraordinary successes of the sciences have lowered confidence in some of the tenets of traditional religions. Insofar as these pertain to explanations of the phenomena in the physical world, science has replaced most religious claims. However, the religious framework also includes other elements besides explanations of phenomena, such as feelings of reverence, a sense of sacredness, profound gratitude, and an ethical framework. These do not arise from scientific discoveries, theories, and explanations, but they are no less important for individual serenity and collective sanity.
It is in this context that religious naturalism arises. Religious naturalism holds that all the positive values, experiences, and attitudes that ensue from traditional religions are accessible via a purely naturalistic view of the world. Furthermore, it also shields one from features of traditional religions such as superstition, bigotry, and unscientific explanations of natural phenomena. It insists that there is no need to assume the existence of the supernatural, or of a God endowed with the characteristics of omnipotence, omniscience, compassion, mercy, and the like. Thus, religious naturalism denies the existence of heaven, hell, and transcendent beings. It maintains that the physical world in all its complexity is the only reality. In the terrestrial context, a plethora of living organisms have arisen, of which Homo sapiens is perhaps the most sophisticated. From the complexity of the human brain have emerged capacities such as thoughts, values, and abstract concepts.
Religious naturalism holds that all of the cultural, conceptual, and historical aspects of humanity can also be explained from the naturalistic framework. Furthermore, religious naturalism regards naturalism as the only valid approach to reaching any rational and coherent understanding of the world. By this view, when the naturalistic worldview is wisely adopted, it can add meaning, purpose, and fulfillment to life as effectively as any religion.
Religious naturalists fully appreciate the element of community building. The idea of people being bound together in a common worldview is implicit in the word religion. (The word has been traced to the Latin ligare, to bind.) Religious naturalists discuss their framework from mildly varying perspectives. Some are not very different from secular humanists in that they separate themselves from anything religious. Some are avowed atheists who are against all organized religions. Some have suggested that our universe is just one of many-one species of universe within a multiverse (in the Darwinian sense). By this view, our universe has evolved over time, has grown by adaptation, and is destined to annihilation. Some religious naturalists argue that religions are inevitable cultural delusions to which most humans are subject. But there are also religious naturalists who take the values of traditional religions seriously, and even adopt some terminologies of traditional religions, such as mystery, gratitude, and reverence, giving these terms new interpretations.
What unites all religious naturalists is the conviction that gods and religions are not, as the traditions claim, revelations of the transcendent to a chosen few, but natural products of cultural evolution. As to heaven and hell, religious naturalism holds that the transcendental realities enunciated by traditional religions can be more meaningfully conceptualized in other ways. Religious naturalists try to understand the nature and origin of belief in God; they seek its roots within the brain, neurons, and genes. In their view, religions have emerged, not unlike organisms, from the contingencies of survival and adaptation. Religious naturalists exert to build a theology based on biology and neurology, relate mysticism to molecules, and probe into the sacred depths of nature.
Religious naturalists seek meaning from within the natural world, trusting science and art, traditional wisdom and poetry. They do not separate humanity from the rest of the natural phenomena. They are deeply interested in issues of peace and justice. As with religious adherents, religious naturalists also experience feelings of deep joy and reverence Religious naturalists write books, exchange views, and organize meetings in which they explore the countless implications of their worldview in the modern context. Religious naturalism, however, is not an organized system of thought or philosophy, but a movement in which many scholars, thinkers, and scientists participate.