It is true. Theists misinterpret atheists all the time (the other way round is also true), often leading to confusions, misunderstanding, conflicts, undermining of each other etc… I read up a little bit and offer the following view.
The two keywords to know, in order to be able to grasp this concept, are belief and knowledge. Both words are simple — so I don’t have to explain.
Simply put, atheism and agnosticism are neither opposing views nor synonymous. These are two different concepts and you can be both.
So there are really four buckets and you could be in any one of them. You can believe in god and claim to know so (gnostic theist, GT), or can believe in god and not claim to know so (agnostic theists, AT), or not believe in god and claim to know so (gnostic atheist, GA), or not believe in god and not claim to know so (agnostic atheist, AA).
So along the belief-axis, the pecking order might be GT, AT, AA, GA and along the knowledge-axis, the pecking order might be AA, AT and GA/GT being the “same bunch”. Or in simpler terms, GT will treat AA like impostors and tolerate ATs (but why ;) ). From an AA point of view, Gx don’t know what the hell they are talking, and AT is marginally better.
At the end, it doesn’t matter which of the four types you belong to, it only matters you treat people regardless of the type.