Blasphemy has less to do with the physics of the universe and more to do with the fear of insignificance. If people are permitted to mock or defame the religious uber being of whatever religion happens to dominate the culture, it demeans the greatness of that entity. And, since there is no such thing as a god to meet out punishment, the only way to instill fear and obedience in the flock is for the human believers in that diety to punish the maligner, usually physically and in a horrible manner so as to scare the rest of the population into quiet submission to the leaders of that relgion. In areas of the world that are wracked by poverty and violence, it is even more important for them to fear not believing, as they might be less willing to accept their lot and fight against the ruling, supposedly god chosen leaders.