Great question don't you think?
And of course, the irony is that anyone who suffers from delusions wouldn't know that they do so otherwise they would not suffer from delusions in the first place; unless they are very creative people such as artists who rely on living in Lala Land in order to get their creative juices flowing.
But, how about those who get sucked into the ugly vortex of religion who don't realise that their new-found elation about the meaning of life is no more than a farce and that they have to commit themselves to living a false, isolated life full of lies and deception in order to "keep the dream alive"?
Well, worry no more because here is a simple fun test to find out exactly how deluded you really are. Just answer the questions and, at the end of the quiz check the answers to find out whether or not you should be pushing lawn-mowers upside down in a secluded estate.
Question 1: Do you believe there is a God?
Question 2: Do you really believe there is a God?
Question 3: Do you absolutely, without a doubt really believe that there is a God?
If you answered yes to question 1: That's fairly normal and you are maybe saying you are religion-curious for the heck of it or "just in case" there might be a God, in which case, you're only kidding yourself because, if there really is a God, he will be very p'd off over your two-way bet and will send you "straight down there" when you fall off the perch.
If you answered yes to question 2: We all know what it's like to lose loved ones, have family issues or even be teased at school or have suffered from bed-wetting well into puberty but you know that your delusions are no more than an escape and you will get over it in time.
If you answered yes to question 3: This is wasted text because nothing short of a full frontal lobotomy will ever convince you that you are profoundly deluded. Even though there are many highly-qualified mental-health professionals out there to help you we know that you will continue to self-medicate and talk to your imaginary friend. Apparently there is an increasing demand for good basket-weaving and number-plate stamping.