I have no idea about the average person, or how you would even measure or quantify what it means to "actually" believe something you claim to believe. I suppose you could say the same thing about any belief system, even empiricism or scientific rationalism. How do you prove that you "actually" believe in anything?
I suppose you would "measure" how they act rather than what they say. If someone says I'm willing to "die for Allah" and then actually becomes a suicide bomber, that's pretty solid evidence.
