Atheists hear this complaint a lot, sometimes justified but in practice mostly derived from two circumstances:
- - a remarkable ability of theists - some of them, present company excluded for lack of evidence - to find insult in almost any observation or criticism that crosses their particular dogma.
In particular, the habit theists have of claiming sincerity of some belief as adequate grounds for respect - not only of the believer, but also of the belief - in matters of physical and historical fact, keeps running them into insult from people who are simply observing that the belief is nonsense.
- - and the fact that theists do not live in a world of atheists talking freely, and are not accustomed to hearing their own beliefs described in the same language they use for others' beliefs, their own ideas treated equally with the ideas of others, their own status as theists not taken as recommendation for their character or actions. This loss of status, as when a prince gets a parking ticket, seems to strike them as intrinsically insulting.
So your average theist seems oblivious to the implications of, say, the common newspaper account of someone apprehended in wrongdoing bringing their theism into the courtroom as a factor to be considered in sentencing. Do you see how easily such a worldview could lead to taking insult ?