Most skeptics and all atheists think of religion as a human invention because (1) religions differ greatly from one another, and (2) religious views are often culture-specific. Let me address each in turn.
Religions differ from one another
It is reasoned that if God exists and is knowable by man, everyone should be in basic agreement about who he/she/it/they is/are. Instead, religious views are often very different: God is one, God is many; God is personal, God is impersonal; Jesus is God incarnate, Jesus is a heretic; the world exists, the world is an illusion. Skeptics conclude that either God is unknowable by man (in which case the whole question of religious truth is irrelevant), or more likely, God does not exist to begin with. Religion is just a human invention, and the variegated expressions of religion reflect the variegated creativity of man.
Both conclusions are flawed in that they confuse epistemology with ontology. Just because people have different answers to the same question (epistemology) does not mean there is no correct answer (ontology), or that no one knows the correct answer. If ten math students give ten different answers to the same math problem, it does not mean there is no correct answer, or that none of the students possess the correct answer. Difficulty in knowing a thing does not translate into an inability to know that thing, or the lack of a thing to be known in the first place. At best, the existence of a multiplicity of religious beliefs only highlights a possible epistemological problem associated with knowing God. It is not a good argument against the existence of God/gods (an ontological issue).
If the Bible is to be believed, the problem is not so much with epistemology as it is corrupted volition. Deep down men know the one true God, but in rebellion they will to suppress that knowledge, making up religions that are more palatable to their tastes. Think Romans 1-3.
Religious views are culture-specific
This is the more important of the two reasons. When you look at religion on a global level it becomes readily apparent that religious perspectives are often specific to a particular culture or geographical locale. It is claimed that the most reasonable explanation for this phenomenon is that religions are mere cultural inventions passed on from generation to generation. They don’t spread beyond the culture because—as an invention—they are not the sort of things that are accessible to, and discoverable by men outside the community in which they arose.
The observation that religions tend to be isolated to a particular culture and geography is true. The question is why that’s so. Is it because they are human inventions, or is there some other reason? I think the atheist is largely correct when he concludes from the multiplicity of geographical and culture-specific religions that religion is a human invention. Indeed, because they are markedly different from one another, they can’t all be right about God. At best, only one of them can be right, relegating the rest to human imagination. Where the skeptic errs is in his conclusion that all religions must be mere human inventions. Indeed, one religion could be the correct one.
But how could it be that only one culture has the truth about God, and none of the others (this isn’t to say there is no truth to be found in false religions, but only that on the macro-level, one religion is true and the rest are false)? It could be that God only chose to reveal Himself to one people, or it could be that all but one people remained faithful to the truths God revealed to them about Himself. It could be any number of other reasons as well. The point is that we need not conclude all religions are mere human inventions because they tend to be cultural and/or geographical-specific. That conclusion does not follow from the premises.
My next post will address a similar argument against religion.