Your missing the point. You can have no grounds given empiricism, per definition, can have no grounds. Faith can, per definition, have grounds.
All it takes is for
a) God to exist
b) God to communicate with man.
It can have grounds and it can make the statements without being necessarily arrogant. You said it
was arrogant which denied the possibility of grounds.
One can say you are being arrogant - for you can have no grounds. But one cannot be so sure in the opposite direction.