Paul W. answered • 05/12/19
Dedicated to Achieving Student Success in History, Government, Culture
Blasphemy, as you noted, is based on the notion that one or more supreme beings are concerned with what their creations, specifically human beings, say about them. Essentially, for those who subscribe to a particular Faith, the issue of blasphemy is a matter of the individual's relationship with his / her creator(s). The supreme being(s) plays a role similar to one's parents and, therefore, is deserving of the same love and respect that is at the heart of the average person's relationship with their parents (at least, in the ideal circumstances).
Obviously, the notion of blasphemy is predicated on a belief in the existence of one or more supreme beings. Thus, one has to subscribe to a particular Faith that includes the existence of one or more supreme beings who are responsible for creating, through whatever process, the human race. In this respect, the notion of blasphemy is consistent with 'The Golden Rule', that is, do on to others as you would have them do on to you - i.e. if you want people to be nice to you, be nice to them.
One of the chief issues surrounding blasphemy is what a particular Faith system (religion) qualifies as blasphemy. How broad is a particular religion's definition of blasphemy? Directing hateful speech towards one's creator is, so far as I know, uniformly identified as blasphemy (not to mention that it's generally not a good idea to get on the wrong side of a supreme being...)
However, some Faith systems / religions extend the definition of blasphemy to include questions regarding what the specific religion presents as the correct teachings of the supreme being(s) (as defined by the leaders of said religion). This, of course, is problematic. Human beings are equipped with brains with which to think and, if we accept that we are created by one or more supreme beings, then our ability to think is an intentional faculty with which our creator(s) equipped us. Why, then, would our creators resent our use of the faculty of thinking if they gave us the ability to ask questions. Obviously, an individual can both show respect for a religion and ask questions about that same religion. Respect and honest inquiry are not mutually exclusive. (Moreover, it strikes me that a religion that can't withstand being respectfully questioned by mortal human beings is on shaky ground...)
Lastly, regardless of how one may feel about the religion someone else practices, it is a matter of respect for the individual that you don't intentionally speak in a blasphemous manner about their religion.
