The worldview or philosophy of anti-supernaturalism is marked by a complete rejection of the concept of a spiritual or supernatural realm which coexists with the natural or material realm. This worldview goes by different names in different academic and popular circles; some of its other names are physicalism, materialism, and philosophical naturalism. Regardless of what you call it, the idea is the same: there are only material realities, no immaterial ones exist, and the idea that they could exist, or at least that we could ever know whether they exist, is regarded with a high degree of disdain.
What’s the reason for this? It’s a cultural phenomenon that slowly developed in the west as a result of an increasingly high position of authority being given to empirical science and human reason over and against divine revelation as a result of the Enlightenment. Very closely-related to this is empiricism– they idea that we can only know that which can be tested directly with the four senses. Philosophically speaking, empiricism didn’t prevail as a worldview for very long, because it quickly became apparent that it didn’t pass its own test! The statement “We can only know that which is testable by the senses,” is itself not a sensory statement, but an abstract philosophical one! Thus the very heart of philosophical empiricism is self-contradictory. Yet, the damage was done, and even to this day in scientific circles one can scarcely avoid this kind of thinking.
If we are to ascertain whether or not anything other than material realities exists, there are many ways we can do it, but none of those ways will ever involve direct empirical testing, precisely because it is by definition impossible to directly test for supernatural realities with physical instruments and senses. The idea is absurd from the start, yet that is the test that many anti-supernaturalists demand. “I will believe in the supernatural when I have tangible proof!” By that, they mean they want direct physical proof of the non-physical. One of the chief ways we can realistically decide whether the supernatural realm exists is called abductive reasoning.
Abductive reasoning is, simply put, inference to the best explanation. (Sober, Elliot. Core Questions in Philosophy,5th edition.)
It means we can look at a set of facts and attempt to determine what the best explanation is, all things being considered, for those facts. If there are things about our reality that are not explicable in terms of matter alone, then that means we are justified in seeking an immaterial, or supernatural, explanation for those things.
Why is all this important? It’s probably obvious, but it has a huge bearing on all the big questions of life. If there are no supernatural realities, that fact has big ramifications on issues like the Bible (which speaks of supernatural realities), life after death, and so on and so forth. As a general rule, most atheists tend to also be materialistic in their thinking. God is ruled out because only naturalistic explanations are considered acceptable. What results is “naturalism of the gaps”, where such people feel smugly-justified in assuming (having blind faith) that, regardless of our current inability to provide any satisfactory explanation for something in terms of matter alone, in the future such explanations will manifest themselves. Ironically, it’s the very same thing these types of people often accuse theists of doing, just in the opposite direction. The issue of worldviews is a very emotional one for people who truly understand the far-reaching implications they have. This means many people, often without realizing it and for reasons that have nothing to do with logic or evidence, rule out from the start the conclusion they do not want to believe in. As Blaise Pascal said, “The heart has its reasons of which reason knows nothing.”
At this point I’d like to recommend a book to you, the reader, that will be immensely helpful in shedding some light on this issue. “Beyond Death: Exploring the Evidence for Immortality” by Gary Habermas and J.P. Moreland does an excellent job of providing both evidence and argumentation for the reality of the supernatural soul and life after death. Please find a way, if you can, to read this book.