David Wilkerson emphasizes the constant threat posed by the devil to believers, urging Christians to be aware of his tactics to avoid being taken advantage of. He highlights that Satan is actively waging war against God's people, knowing his time is limited, and warns against spiritual slumber. Wilkerson reassures that when believers move towards Jesus, the enemy is rendered powerless, as illustrated by the scriptures. He encourages vigilance and resistance against the devil, reminding us of God's promise of escape in difficult times.