It should be thought-provoking at least, as it is the kind of thing that renders the "infected" person oblivious to the fact that he does, in fact, have it. A believer with a hardened heart probably does not realise it. In fact, he may think he is totally right in whatever matter is on the table. Only by God's grace can this be reversed, as the Holy Spirit points out truth and sin, and we have the spiritual sensitivity to respond correctly. The opposite would be to continue blinded by our pride, assuming everyone else is wrong.
Lord, give me a sensitive heart that is always on the alert. My deadliest enemy is probably the one inside.
("For they considered not the miracle of the loaves: for their heart was hardened.")