1.die off before anything happens. 2.Update the religion to accomodate the blasphemer. 3.create a new religion similar to the one it came from, except for the beliefs that the blasphemer didn't approve.
4. Kill a religion as people move away from the old beliefs.
Does it have to be religious, cant it be blasphemous to insult a honored king?
I suppose it's possible if the king is regarded as sacred. Though such beliefs about royalty are usually the result of religious views.