A recovery of the old sense of sin is essential to Christianity. Christ takes it for granted that men are bad. Until we really feel this assumption of His to be true, though we are part of the world He came to save, we are not part of the audience to whom His words are addressed.
When you are interviewing someone, you have a chance to follow up, to press, to dig in. In a debate there's 30 seconds for the other guy, too. And the goal is to get them to engage with each other, not to engage you necessarily.