It depends what god you serve. Some people serve alcohol, others serve hookers and porn, others serve cigarettes, others serve gluttony, others serve recreational drugs, others serve greed, others serve pride, others serve wrath, others serve envy, others serve sloth, others serve gambling, etc..
If you mean the Christian God then we have the one that says eye for an eye, and we have another one that says you should forgive.
Then you have one god saying you will be judged by your sins, and another one saying the justice of God is mercy.
You have one god that avenges, and another one that has compassion.
It sounds like the one that says whatever you do with others you do it with me is the greater one or the one above.
Apparently the one above doesn't need to change anything from the previous god, the previous god still exists, but the God above pretty much overrides the stuff from the previous god. It fulfills it somehow from a higher paradigm.
So the one above probably doesn't care for language that much, he probably cares for how you treat people you encounter in your daily life.
Similar to the story that there was a son who said he was going to do the vineyard work and didn't, and another son that said he wasn't going to do it, but did it anyway. I doubt the father of those sons cared about what the one that didn't do the work actually said.
In other words, depending of the god you talk about the meaning of blasphemy will differ.
For one god it would be something as simple as saying the words, and for the other one it would be something like the Spanish Inquisition.
Similar to the stuff the gnostics talk about:
https://youtu.be/cZkjoWlnh3M