When debating a religious person, or simply asking a religious person why one should believe in a particular iron age deity, a very common answer one might hear will be one version of the following:

‘How could the universe create itself? And even after the universe started, how could so many physical constants and variables assemble themselves in such a precise way as to allow the development of complex life and of human consciousness? All of this leads us to the conclusion that there must have been a supreme being outside of the natural universe that brought all of this about. After all, it takes more faith to assume that all of this came about by random chance rather than by deliberate creation’.
The first thing to notice about this type of faulty reasoning is that it attempts to establish a claim of knowledge on the grounds of ignorance. In other words – ‘Because I DO NOT KNOW how the universe, or complex life, came about, I DO KNOW that there is a god. This logic is so faulty that it could not even be elevated to the rank of the classic non sequitar fallacy, where the latter claim does not follow the former. In this case, the claims don’t even go in the same direction – they fly in completely opposite directions – one claiming not to know, and the other claiming to know. It is not just for the sake of denigration that claims like this are called childish. Children have a well known tebdancy of KNOWING that such characters as Santa Claus exist because they DO NOT KNOW how the presents could have otherwise appeared on Christmas morning, or KNOWING that the tooth fairy exists because they DO NOT KNOW of any other way their tooth could have been replaced with a dollar bill under their pillow.
To be sure, no adult wants to be compared to a child, but one simply cannot ignore the fact that religious reasoning of this sort is purely and utterly childish.
Socrates famously said “I know nothing except the fact of my ignorance”. It is perfectly logical, and even admirable, to simply admit that you do not know how something happened or how something works. It is not the most comforting thing to have to admit, but an important one none the less. This act of admitting one’s ignorance does not mean that one is resound to never know these things. In fact, i would argue that the only way to learn new things is to admit that one does not know these things in the first place.
In a world of Moore’s law, new scientific discoveries, a burgeoning field of neuroscience, and an ever expanding understanding of astronomy and the cosmos, people who should be excluded from the debate to begin with are the ones who claim that they already have all the answers, and that everything mankind needs to know has already been revealed to ancient middle eastern tribesmen who didn’t even know enough to separate their food from their excrement – founders of “great religions” who knew less about the world than any first grader knows today.
Next time you encounter a religious person who claims to know that an omnipotent omniscient deity created the universe, politely ask them the simple yet devastating question – How do you know? If the answer boils down to a lack of knowledge how the universe could have otherwise come about (usually expressed in patronising tones), you will know that you have just uncovered the fallacy.