Blasphemy can be a lot of things — or, rather, a lot of things can be considered blasphemous. Questioning whether a religion is true (esp. if it’s the majority religion), criticizing a religion’s beliefs or doctrines or rules of behavior, mocking a religion or deity or the holy people of a religion, telling a religious joke …
What someone else considers blasphemy may be something I consider funny. Or rude. Or insightful. But, regardless, blasphemy laws have no place in a free society — especially as they are all too often used as cudgels to oppress religious (or irreligious) minorities and dissenters.
And blasphemy laws are also far too often simply ways of coddling the feelings of the devout, or or protecting the status/dignity of the priesthood. It seems unlikely that God is harmed by being mocked or insulted or denied — and, if so, God can do something about it. No, we’re talking about humans being distressed or offended or having their feelings hurt or feathers ruffled. And if someone’s faith may be shaken by hearing a blasphemy uttered … their faith doesn’t sound all that strong.
As a general rule, “Don’t be a dick” is a good way to behave. Being blasphemous just to torque others off is rude and usually counterproductive to any useful dialog. But while it may may lead to social consequences, such behavior — or blasphemy for any purpose — doesn’t deserve criminal penalties. Especially since one person’s honest expression of their own beliefs (or casual use of humor, or even a drawing of Jesus saying, “Don’t be a dick”) might be another person’s blasphemy.