Brad Hirschfield, writing in the Huffington Post reflects on the real sin of Stephen Hawking in denying heaven:
Stephen Hawking, the world famous cosmologist and physicist, declared in an interview published in the May 15 edition of England's Guardian that "there is no heaven." Whether he is correct or not is not something anyone can know for sure. We can believe as we choose, but we cannot "know" as a matter of fact, either way.
Having made that claim, I am probably picking a fight with both some of those who believe in heaven and some of those who do not. The believers may object to my distinction between knowledge and belief. he non-believers may object to my assertion that they cannot know if in fact they are correct. ....
In no way however, does the absence of scientific evidence for the existence of heaven mean that heaven is for idiots, as Hawking suggested in further comments to his interviewer. Having asserted that there is no heaven, the professor went on to "explain" that heaven is "a fairy tale for people afraid of the dark." That kind of denigration of other people and their beliefs is not only unnecessary, it is precisely the kind of obnoxious behavior that too many religious folk dole out to non-believers.
In denying the existence of heaven, Hawking definitely commits a sin -- that of speaking badly about others. Hawking's sin, in Jewish tradition, is called lashon ha'rah, and interestingly it is not limited to speaking falsely. Rather then being defined by the factuality of the utterance (there are other categories of transgression to cover that), lashon ha'ra is defined by the callousness, mean-spiritedness or insensitivity of the utterance, even if it is true. There is no question that Hawking crossed that line and for that he should be held accountable.