Caitanya Mahaprabhu has recommended that everyone chant the Hare Krishna mantra just to cleanse the dust from the heart. If the dust of the heart is cleansed away, then one can actually understand the importance of the holy name.
Nectar of Devotion, Chapter 12,
Living beings who are entangled in the complicated meshes of birth and death can be freed immediately by even unconsciously chanting the holy name of Krishna, which is feared by fear personified. — Srimad Bhagavatam, 01.01.15.
Terrorist guns can kill the material body, but the Holy Name of the Lord can kill the enemies within the mind of the person.
Krishna is present fully in His holy name and this is realized by the humility and sincerity in our chanting.