The argument from religious pluralism (one form of it anyway) tries to argue from the wide variety of past and current religions as evidence against one religion in particular. Since Christianity is a politically correct target as of late, for sake of having a specific example I’ll pick on Christianity. There are good and bad ways to approach this. I’ll describe a bad approach before describing a better one.
A Bad Approach
There are numerous claims about gods as evidenced by the numerous religions and numerous people who sincerely believe in them while also sincerely believing that their views about gods are justified. If the majority of people are mistaken about gods despite their sincere belief, how do you know your view about gods isn’t among the majority who are mistaken?
Why is this bad? Well, atheism also makes claims about gods (saying that there are none) and would presumably be susceptible to the same problem:
There are numerous claims about gods as evidenced by the numerous religions and numerous people who sincerely believe in them while also sincerely believing that their views about gods are justified. If the majority of people are mistaken about gods despite their sincere belief, how do you know your view about gods (atheism) isn’t among the majority who are mistaken?
The atheist could say that not all claims about gods are equally probable and that we have good reason to award atheism a higher probability than e.g. a monotheistic religion which professes an omnipotent, omniscient, and perfectly good deity due to things like the argument from evil and the presumption of atheism. The mere existence of competing claims doesn’t do anything to show that atheism is false or unjustified; one would actually have to look at where the evidence points among these competing claims.
The Christian could give the same sort of response, noting that one can’t point to the mere existence of competing claims as sufficient grounds to think Christianity is false, and that one would actually have to look at where the evidence points. The Christian may well be mistaken about where the evidence points, but the fact remains that the mere existence of competing claims just isn’t enough. The same, after all, holds true for atheism.
So far the argument from religious pluralism looks to be in serious trouble. Is there a better approach?
A Better Approach
We should reject the all-or-nothing dichotomy where an argument either conclusively proves a position or it’s worthless. Consider criminal trials where each individual bit of circumstantial evidence carries little weight by itself but taken together provide a powerful case. Sometimes legitimate evidence against a belief simply makes a belief less certain than it otherwise would be. I think that’s the approach we should take for the argument from religious pluralism. To illustrate the idea, consider these two possible worlds;
World A: Christianity is one of many competing religions; most religious people are not Christians and there are widespread polytheistic faiths, with the historical percentages of competing faiths (including polytheistic ones) being the same as they are in the real world.
World B: Christianity is the only religion; all people are Christians except for atheists and agnostics.
Consider the point of view of the Christian: world A implies that for people who believe in the supernatural, most people go wrong—often horribly wrong—with their supernatural beliefs; whereas the description of world B doesn’t imply that. For those who come to accept the supernatural, the existence of severe human fallibility in arriving at supernatural beliefs is far more apparent in world A then it is in world B, since most who accept the supernatural in world A are not Christians. All things considered then, the rational Christian should be less certain of her faith in world A than world B.
One could dispute the extent of the evidential force the argument from religious pluralism has, but the fact that it has at least some evidential force seems clear. A world like world A is far more suggestive of human fallibility than world B is with respect to deciding which supernatural belief is true.
Double-Edged Sword?
At this point the Christian could concede that the argument from religious pluralism has some evidential force against Christianity while arguing that the argument from religious pluralism also has evidential force against atheism (numerous competing beliefs about gods illustrates that beliefs about gods are quite fallible, and atheism is a belief about gods), so the overall effect of the argument is that it places a pox on both houses, and doesn’t leave either one better off than they were before.
While this response isn’t completely without merit, it also has its problems. First, how do religions generally arise given that the majority are false? A Christian might say the cause is demons, but there is good reason to doubt this even on the Christian worldview. Surely if demons were behind the bulk of religions, the result would be religions that are more, well, demonic. I’m not denying there haven’t been any religions that call for human sacrifice, but we also find that many religions have some version of the golden rule, and the ethical teachings of many contemporary religions look no worse than the Mosaic law of the Old Testament, a law system that says (among other things) that one who curses their father is to be killed (Leviticus 20:9) and that two men having sex must be killed (Leviticus 20:13), laws so barbaric that even most Christians and Jews disavow their use for the current culture. The best and most likely answer is that the false religions (at least by and large) are not the results of demons but the delusions of ordinary people.
Religions generally emerge from (to put it bluntly) craziness. Somebody’s intuitions of reality go seriously off kilter and they think e.g. some supernatural entity told them stuff when nothing of the sort happened; instead it was a delusion. Acceptance of a religious delusion depends heavily on where one grows up and what culture one is in. Lots of people give into delusions based on too little evidence, such as simply believing what they are told. Many (most?) Christians are among those who believe their faith simply because that is what they have been told.
In contrast, the atheist can take an initial skeptical point of view to simply not believe a deity exists any more than she would believe a flying magical horse exists unless she has sufficient evidence. Most of us would typically take a skeptical stance when told that someone saw a deity descend from the clouds and shoot lightning from his fingertips. The atheist simply extends the same natural, healthy skepticism towards all gods in general. So here we have a relevant asymmetry between the Christian and the atheist. Clearly there are massive delusions going about when it comes to picking a religion to believe, whereas atheism stands apart and simply applies the normal, intellectually healthy skepticism towards gods.
The typical religious adherent believes their religion is true because that’s what they’ve been told, but clearly being told that a religion is true is insufficient grounds when numerous competing religions all make their own truth claims. Against this, the argument from religious pluralism is particularly powerful, more so against the typical believer than the typical atheist, because in contrast to the typical believer, the typical atheist believes atheism not because someone told them it is true, but because they apply the same sort of natural, intellectually healthy skepticism towards all gods.
Notice I’ve been qualifying with “typical” believer. There are some religious believers, such as Christian apologists, who after studying apologetics come to sincerely believe that the evidence is on their side. When Christian apologists present an evidential case for their faith, as in a debate, pointing to the existence of competing claims is less effective an argument than with Christians who believe their religion simply because they’ve been told it’s true. Against Christians who present an evidential case for their belief, one would have to address the evidence more directly, such as the argument from evil. That said, atheism can be based on commonsense skepticism towards extraordinary claims and even Christianity is heavily dependent on the testimony of those claiming to witness extraordinary events in a world where people making extraordinary witness claims about gods are frequently delusional. This surely ought to make the Christian less certain of their faith than they otherwise would be.
An “Argument from Hiddenness” Approach
Another approach, perhaps the most effective one for religions that teach that an omnipotent, omniscient, perfectly good, all-loving God wants to enter in a loving relationship with us in mortal life, such as Christianity (at least, this seems to be a popular variety of that faith) is the following. If there were such a God as this who wanted to us to know e.g. that Jesus is God incarnate and died for our sins, it seems likely that God would not have left such widespread confusion with sincere religious adherents following false religions. It seems more likely that God would reveal himself clearly, widely, and unambiguously to all who genuinely seek him instead of allowing sincere seekers of God follow false faiths in the religious imbroglio we observe. God is instead relatively hidden. Moreover, since we can reasonably say people who sincerely seek God following a false deity is a bad thing, we could also make the argument from religious pluralism a sort of argument from evil, since a perfectly good, omnipotent, and omniscient God would be allowing this bad thing to happen.
Conclusion
The argument from religious pluralism, at least the variety that merely points out the existence of competing claims, is not sufficient in itself to show that a particular religion (as Christianity) is false or unlikely. This shouldn’t be surprising; in general, the mere existence of competing claims is insufficient to show that a particular claim is false, as illustrated by the fact that atheism is likewise one claim among many when it comes to beliefs about gods.
That said, the argument from religious pluralism does make Christianity less certain than it otherwise would be, as illustrated in the case of world A (many competing religions, including polytheistic ones, as in the case of the real world) and world B (Christianity being the only religion). All else held constant, humans would appear to be substantially more fallible in world A than in world B when it comes to picking supernatural beliefs, which ought to make the rational Christian less certain of her faith than she otherwise would be. Thus this argument from religious pluralism carries at least some evidential weight, though how much weight it carries could be disputed. The argument from religious pluralism carries additional weight when framed as an argument from divine hiddenness or an argument from evil.
