My name is how others identify me, how I introduce and represent myself; it symbolizes my character and nature. If someone disrespects my name, I take it personally.
Taking someone’s name in vain is to use it in a light, casual or inappropriate manner, for any other purpose than to refer to them. Doing so treats their name as if it’s void of proper meaning, empty.
So God is grieved as we speak His name in vain (Ex 20:7), lightly, in an empty manner, when we aren’t referring to Him. To use His name as an interjection or expletive, as an expression of intensity or emphasis (e.g. J!, JC!, OMG! or GD!), is ultimately to disregard and despise Him. This is done so casually today, even by those who profess to believe in Him, we might have become desensitized, callous to it. God never gets used to it.
I never hear any false deity’s name ever taken in vain, only the true. What would be the point of insulting a non-entity? There’s only substance in trampling deity underfoot if He’s real, if He’s angered by the disrespect.
Should it grieve us, as it does Him? I think so.