Sentence:  Hence , if what is in question <WSD>is</WSD> whether in a given theology myth is or is not completely rejected , it is unimportant whether only a little bit of myth or a considerable quantity is accepted ; for , in either event , the first possibility is excluded . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)