To be honest, I think the Q are the masters of Bravado. It seems to be, that the franchise lightly hints at this too.
1. We know a Q dies, on Earth, due to a tornado. [I hope im recalling correctly, havent seen that episode for a while]
2. Q is shown to be 'stripped of his powers'.
3. There is a civil war in which Q die.
4. Q seems intimidated by Guinan, and she seems poised to defend herself. A ridiculous notion if it were a true 'god' however she seems serious enough. He even calls her an 'imp'....which implies some sort of impish behaviour against the continuum.
I have always suspected the Q exaggerate their power to portray an aura of invincibility to the less developed races [who have insufficient resources to prove otherwise]. No doubt they are vastly powerful....but not omnipotent. The mere word makes no sense.