I like Thomas Nagel’s phrase “the religious temperament”. It describes both religious and non-religious people. The following quote by Nagel gives a basic outline:
Existence is something tremendous, and day-to-day life, however indispensable, seems an insufficient response to it, a failure of consciousness. Outrageous as it sounds, the religious temperament regards a merely human life as insufficient, as a partial blindness to or rejection of the terms of our existence. It asks for something more encompassing without knowing what it might be.¹ (my emphasis)
A slightly different but overlapping take is that by Bryan Magee. He writes:
Not being religious myself, yet believing that most of reality is likely to be permanently unknowable to human beings, I see a compelling need for the demystification of the unknowable. It seems to me that most people tend either to believe that all reality is in principle knowable or to believe that there is a religious dimension to things. A third alternative – that we can know very little but have equally little ground for religious belief – receives scant consideration, and yet seems to me to be where the truth lies.²
Given our limited capability to understand things, I find it amazing that we got as far as we did in explaining the reality that we assume to be a part of, from the quantum level to the cosmological level. I also trust we will be able to push the boundaries of our knowledge even further. But to assume that one day we will understand everything seems presumptuous, given that we are dependent on the data that we can gather. We simply can’t see beyond the visible universe. Many theories that try to answer some of our biggest questions can not be validated, because of this limitation. And to say we already understand everything, because we’ve got the theory of cosmic inflation (or “the Big Bang theory”—which is not exactly the same) is folly.
I like to think that most people that rely on science for an explanatory framework of reality allow for at least some uncertainty. Clearly scientists don’t understand everything yet—and that’s okay. As I see it, many religious people don’t allow for that uncertainty, albeit in slightly varying degrees. Usually their supreme being explains everything, and as a bonus magically endows their personal existence with meaning. Some religious people claim even certainty in every detail of the creation, because it has been spelled out in their holy book.
In a variation on the balance between certainty and uncertainty certain religious people stress that their god is beyond understanding for human beings. Why does their god allow millions of children to die every year? Well, God’s ways are mysterious. Why does their god allow for millions of people to die in natural disasters? Perhaps it was some kind of punishment. But surely God has a plan. While we may not know exactly what it is we can rest assured as long as we have faith.
The total lack of proof for a god or other “supernatural” beings or layers of reality is a remarkable feature of religious systems. How can people be certain about the supernatural? Personal experience (that cannot be shared) mostly. Also simply the feeling that surely there must be a God that explains otherwise difficult to comprehend aspects of the world. And surely there must be life after death, because, you know, don’t you feel that your mind is independent of your body? And surely there will be punishment for the wicked, because the injustices of this world are simply unbearable. Etc.
Some religious people accept the explanatory power of science, and explain their faith solely in a personal connection or experience with the divine. Others think that truth can be found in “divinely inspired” scripture. A few try to adopt some version of the scientific method to prove the divine, but their theories are too ad hoc to be accepted other scientists.
Personally I think that the need for cosmic certainty is childish. Really problematic is that many religious people claim that their totally baseless claim to the truth implies that they can tell everybody else how society should be organized and how people must live their lives. The peak of hypocrisy of religious people is their effort to limit access of their children to real world knowledge (like for example the fact that here are literally thousands of religions with competing truth claims) and real science. This to assure that the indoctrination of their children in the proper faith succeeds. It reveals that in fact these parents know that their truth claim is baseless and indefensible, but want to stick to it anyway.