@reasoning logic,
I like Sam Harris. He is an interesting cat. Good speaker. However, I don't think his fridge-diamond analogy quite works.
A goodly part of how we decide what is reasonable and rational is taken from queue's given to us by others. From the time we are children we are raised around religious people and so as we get older, we unconsciously normalize the existence of God.
We aren't raised with a normalization of diamond-fridges.
I get what he's saying - in a vacuum. His logic is correct. But 'on the ground', as a practical matter, I don't think they are comparable. Some of my family is religious, their kids are between 5 and 7 and the kids are already talking about God as a real entity. Nothing drives the above point home like this.
It is in this sense that I am uncomfortable with calling religious people delusional. It all depends on your definition. Comparing a religious person with a schizophrenic who hallucinates and is paranoid, for example, does a disservice to the way we process information.
If you were to broaden the definition of delusional to include religious people, if you continue to its 'logical' conclusion, you would wind up with all of us being delusional about some things. In fact all of us perceive falsehoods, not just from logical errors or mechanical failures of perception, but psychologically. We all have beliefs that are unconsciously distorted to protect ourselves (our ego). In this sense then, with some things, we are all 'delusional'.
So, at the least, you have to qualify what category of delusional you are talking about. However, because that word is so 'charged', I would recommend using a different word entirely.