04/11/2021 at 4:01 pm #670Argumentative AtheistKeymasterPoints: 99,786
In a previous discussion I explained the definition of a mental illness from a common usage point of view and a clinical point of view . In both cases religion does not count as a mental illness. In that discussion I promised to write on the subject of religion as a delusion, which is another claim often made by atheists and irreligious people.
We have to be careful with the term delusion, because there are multiple common use cases for the term. So to start we will define two different contextual versions of common usage for the term. We will be using Merriam-Webster as a source for these definitions . Version one, the version that causes the most confusion, is:
“something that is falsely or delusively believed or propagated”
In this context religion clearly is a delusion. That being a false belief. By using this definition we are essentially admitting that everyone is deluded to some degree and that religious people being deluded means very little and has very few real world implications. I am perfectly happy to agree that religions are false beliefs that are not backed up by a scientific understanding of the world.
However it should be pointed out that this is generally not the context with which irreligious people apply the term, nor is it the context that most people understand the term. When irreligious people state religion is a delusion they usually use a phrase similar to “religious people are delusional”. This is most often understood to mean that the person you are talking about has a psychiatric condition rather than simply false beliefs. This leads onto our second common usage definition of delusion:
“a false idea or belief that is caused by mental illness”
To discuss delusion as a mental illness specifically we will need a psychiatric definition. We will take the psychiatric definition from a paper published in the Industrial Psychiatric Journal “Understanding Delusions”  to ensure a comprehensive definition:
“A delusion is a belief that is clearly false and that indicates an abnormality in the affected person’s content of thought. The false belief is not accounted for by the person’s cultural or religious background or his or her level of intelligence. The key feature of a delusion is the degree to which the person is convinced that the belief is true. A person with a delusion will hold firmly to the belief regardless of evidence to the contrary. Delusions can be difficult to distinguish from overvalued ideas, which are unreasonable ideas that a person holds, but the affected person has at least some level of doubt as to its truthfulness. A person with a delusion is absolutely convinced that the delusion is real. Delusions are a symptom of either a medical, neurological, or mental disorder.”
In this context delusion is clearly used to indicate that the person suffering from delusion have a disorder of some form that actively prevents them from normal thinking processes. Religion, in general, does not fit this criteria. Religion is most often a product of upbringing and cultural background. You will note that in the psychiatric definition of a delusion religion is specifically noted as not being considered a cause of delusion. This is because while religion may be considered a false belief it is not caused by a disorder that prevents people from using normal thinking processes.
Finally, we move onto why you should never state that religious people are deluded, even if you simply mean that they have a belief not supported by science. Professor Andrew Sims has published a paper on the subject in the The British journal of psychiatry: the journal of mental science called “Is Faith Delusion?”  and you can find a pre-print of the paper here . Professor Sims is a Christian and obviously has an interest in considering religion to not be a delusion, but he also has some important points to make. The most important, at least in regards to the use of the term “delusion”, is that while previously delusion was commonly understood to simply mean that someone had a false belief it is now much more commonly understood to mean someone is mentally ill. As Sims points out:
“In English law, delusion has been the cardinal feature of insanity for the last 200 years. It is a mitigating circumstance and can convey diminished responsibility.”
If we wish to call religions false beliefs I personally agree with this statement. However we must be much more circumspect in using the term “delusion” as even if it is not our intention it leads others to believe that we are accusing all religious people of being mentally ill. Being religious is not a mental illness. A mental illness is a psychological or neurological condition that means our thought processes are not working normally. A belief in a religion is a result of cultural upbringing and is not itself an indication of abnormal thinking processes.