In order to defeat the enemy, we have to know who we are and who we are facing. Some one like Muhammad Ali would tell his opponent, "I'm going to knock your face in", then he'll proceed to do just that. That's because he knew who he was and he knew who his opponent was. We has Christians have to know who we are and know who our enemy is, Satan, and that he has no power over us. We have to tell him "Hey Devil, you have no power over me because I'm guarded by the blood of Christ, therefore I rebuke you". If we don't know who we are, and therefore know that our enemy doesn't stand a chance, then how can we defeat the enemy?