Blasphemously tells you how something is said or done: in a way that insults God or people’s religious beliefs. It is the adverb built from blasphemous. You put it with a verb: someone speaks blasphemously, writes blasphemously, jokes blasphemously. It is not a word for everyday chat; it sounds formal and heavy, the kind of word a news report or a religious teacher would use. Though actually, the speaker who chooses it is already judging — they are saying the act crossed a holy line, not merely that it was rude or loud.