The good old OED defines Profane as not relating to or respectful of religious practice; irreverent.
I think most people today would define Profane as a swear word, quite simply. Especially if that person was a Belgian foreign minister reputed to have sent a message via Twitter about a former Canadian Prime Minister, with photo:
Hmmm … very diplomatic, even if it has been disclaimed as belonging to the said Belgian minister! How secular.
Now, of course, the word Profane should not be confused with the closely spelled Propane which of course is a gas that is highly flammable.
There again …!