About a year and half ago, Richard Dawkins wrote The God Delusion. It has created many months of controversy. People are still savaging the book in fierce protest against the evil attack on religion. I wonder what all the anger is about. It seems to me a classic representation of “you protest too much”.
From the standpoint of someone believing in invisible deities of any sort, why would being called delusional be so offensive? If you are certain that you don’t suffer delusions about god(s) then one would think it a rather mild and inoffensive rebuke. Why not laugh it off and go about your business while offering a quick prayer for the poor soul who may have insulted your god?
Is it possible that somewhere in the back of your brain, there is a thought that perhaps you are indeed being delusional? Now, one could see how that would be deeply troubling. If someone told me I was being delusional in thinking that the vaccines I received in childhood would protect me against polio, and there was a little doubt in my mind, I might get pretty upset at being told I was delusional. Being certain in my knowledge, I’d simply laugh about being called delusional and be about my business.
Atheists have been called much worse than "delusional" over the centuries. We've been described as hateful, blasphemous, Satanists, evil, witches, warlocks, wizards, murderers, etc. All of these epithets actually call for action. If you believe them to be true, you would be well advised to do something about the person. These are descriptions of a person who brings dangers into the arena of human affairs and needs to be dealt with accordingly. And, indeed, this is exactly what has happened. Be happy that the atheists who recognize your delusion only hope that you will come to your senses and stop wasting all of our time worshipping unseen and unproven beings.
Most atheists are reluctant to use ad hominem attacks when talking about others. So if anyone calls you "batshit crazy", you might want to keep an eye on us. It's only fair, I suppose. We, after all, are definitely keeping an eye on you.