Do you think other person's property is deserving of due regard? It's not on the definition, but it certainly is. Similarly, a person's belief may be worthy of due regard, even if it doesn't meet the criteria of adherence to reality, but meets another criteria, that of serving the greater good for mankind / society. And, again, notice that I'm not discussing religious belief systems in general, but an individual's belief.
Adherence to reality / evidence-based thinking may be the best possible way to evaluate the intrinsic validity of an idea, but it doesn't tell everything there is to say about the respect that it may (or not) merit.