Of sacrifices I am the chanting of the holy names [japa].
Bhagavat Gita 10.25
It is said, kali-kale nama-rupe krishna-avatara: Krishna descends in this Kali-yuga in the form of His holy name — Hare Krishna, Hare Rama.
Srimad Bhagavatam 9.10.53,
Srila Prabhupada
One who chants the holy name of the Lord is immediately freed from the reactions of unlimited sins, even if he chants indirectly [to indicate something else], jokingly, for musical entertainment, or even neglectfully. This is accepted by all the learned scholars of the scriptures.
Srimad Bhagavatam 6.2.14,
Srila Prabhupada
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.