I have heard many people use an illustration when talking about atheism and its viability. Many will say that they can convert an atheist to an agnostic with this simple illustration. Here is how it goes. If someone claims to be an atheist, you can easily convert them to agnosticism thereby moving them one step closer to theism. How? By asking them a series of questions. First you ask them how certain they are that there is not a God. If they say that they are not certain, that is just what they believe, then you inform them that they are not really an atheist–one who is certain that there is no God–but an agnostic–one who is uncertain about God’s existence. If they say that they are certain that there is no God, then you move to step two. Here you draw a large circle that represents all knowledge in the universe. You ask them to draw a circle within that circle that represents their relative knowledge in relation to all knowledge. Of course, they will draw a much smaller circle within the large circle knowing that they do not possess all knowledge, only a small portion of the whole. Once they have created this smaller circle, you ask them if God could exist somewhere in this vast area that you have no knowledge about. They should always answer yes since that area is their area of ignorance. At that point, it is said, you have converted them from atheism to agnosticism.
Let me start by saying that while this sounds really appealing and irrefutable, it is actually a terrible illustration and represents a very modernistic mindset for the requirements of belief. Why? I am glad you asked. Let me turn the tables on you, the one who believes in God. Why couldn’t an atheist use the same illustration for you? You say you believe in God, how certain are you. Absolutely certain? Oh, okay. Well let me draw this circle that represents all knowledge. Now you draw a circle within this circle representing your knowledge. Oh, that small eh? Could it be that the evidence for God’s non-existence is found outside of your circle of knowledge? Yes? Well then, I have just converted you from a theistic worldview to an agnostic worldview.
You see, it works both ways. Don’t use this illustration. The fallacy on both sides is that it assumes that certainty is only attained and belief is only justified when we possess all knowledge. In order to have true belief, we have to have absolute intellectual certainty about the matter. Since none of us do, we are all necessarily suspended in agnosticism about the matter and must adopt a worldview of hard skepticism. But this is not the case. All of us base our beliefs on incomplete data, but this does not mean that it is inaccurate data. The case for atheism and theism lies not in absolute knowledge of all things, but in the preponderance of the evidence in the knowledge that we do have. That creates an obligation to believe or not believe something. Otherwise we would be suspended in a state of perpetual indecisiveness about all issues, spiritual or mundane, and never have justification for any belief at all.
The key here is that belief is not based upon absolute certainty, but upon reliance in the evidence and information we do have. This creates an obligation to trust. This trust is a combination of intellectual, emotional, and experiential data. It creates degrees of trust according to the evidence provided.
We cover this way of thinking in Introduction to Theology of The Theology Program, session 6.5.