Actually that is postmodernist thought Qliveur. It gets more into the epistemology if how do you know you exist, etc. That was my understanding of it.
Beliefs are something people hold to. Doesn't matter if you are aetheist, Christian, Episcopalian, etc. When you argue your position, you have to tailor your words to your audience. Don't take me as the word here since that was my basic understanding of good ole Aristotle.