A picture of the world (or “worldview”), such as naturalism, theism, or animism, is what we use to make sense of our past and present experience. But it is also and especially how we make predictions about what is likely to happen in the future, to us and to others. Those predictions then guide our behavior.
The extent to which two worldviews are different, concretely speaking, is the extent to which they make different predictions about what is likely to happen in the future. For example, many American evangelicals believe the world will end soon, in some sort of apocalyptic fashion, and that Jesus will return to Earth, riding on the clouds. There’s a “rapture” in there somewhere too, I think. Less dramatically, many religious folk the world over believe that praying about events or people can change how those events occur or how those people are doing. This is a prediction that flows from their worldview.
A naturalist and a theist then, differ on what effects one ought to expect to follow from prayer. They can agree on certain psychosomatic effects perhaps, but beyond that, the theist is likely to expect divine action of some sort, whereas the naturalist expects nothing of the sort.
The reason I am a naturalist is because I have found naturalism’s predictions to be borne out with a consistency that was quite unheard of in Christian circles. The reason Christians struggle with “unanswered prayer” is precisely because they’ve been taught that God answers prayer. When Christian leaders redefine “answering prayer” to mean “whatever actually happens that you can drawn some sort of lesson from”, believers subconsciously sense the switcheroo. Their predictions constantly need to be adjusted because they don’t fit what actually happens. Things happen in the world as if there were no God. And so to maintain the belief that there is a God, and that he answers prayer, the believer’s understanding of God and of prayer has to constantly evolve.
The endpoint of that evolution is predictive equivalence with naturalism.
There comes a point in the life of reflective believers when they succeed in managing their disappointment. Typically this involves giving up any hope for interesting divine intervention in their lives. Debates over so-called “cessationism” for example (roughly, the view that fancy supernatural signs from God no longer occur) are debates over what it makes sense to expect in our lives. The cessationists have realized that impressive miracles don’t happen, and that we shouldn’t expect them. They fit their theology to their experience. Anti-cessationists see that that concession is uncomfortably close to naturalism (to denying that God is the kind of God who can answer prayer), and so find ways to claim as “signs” from God phenomena which fall far short of the really supernatural (exhibit A: glossolalia; a.k.a. “speaking in tongues”).
So a key question to ask believers is this: what difference does your worldview make in terms of your concrete expectations for everyday life? We could put it more bluntly: please make a falsifiable claim by which your faith might be evaluated.
Believers might well return the favor, so here are some predictions I’m comfortable making as a naturalist:
– All my mental striving / praying / hoping / whatever won’t make a difference to what is in fact a matter of luck (e.g. the ratio of heads to tails in an iterated coin toss, the result of an election).
– If the world “ends” anytime soon, it will be because of boring causes: e.g. ecological devastation, asteroid impact, etc.
– When people die, absent radical medical intervention, or zombification, they stay dead (in their tomb say, or cremated).
Etc. You get the picture.
If a believer can’t identify a single thing that makes their worldview predictively different from naturalism, it’s worth asking them if they aren’t in fact naturalists. They might cling to a label (for understandable reasons, even). But if it doesn’t make a difference to your life, it’s probably not worth believing.