You say: 1) Person A: I hold a belief for which there is no proof or rational support. I just have faith in it. 2) Person B: I too hold such a set of beliefs.

You say: 1) Person A: I hold a belief for which there is no proof or rational support. I just have faith in it. 2) Person B: I too hold such a set of beliefs. Mine are different than yours and they even compel me to kill you. What interviewer meant is that this method of thinking arrives at vastly different, even conflicting views, hence it is inconsistent and unreliable.