When people say that Islam is a peaceful religion, are they joking ? B/c I thought...

[BaalzebubFour]

...they were serious but ...? it would make perfect sense if they were just being sarcastic. Kind of like if I said "Sharks are vegetarians. " with a perfectly straight face. Or if I said "There's an omnipotent entity who loves us". I sincerely hope I haven't pissed off any marine biologists.