On 10 March 1975, in London, lecturing on Bhagavad-gita, verse 2, chapter 7, Srila Prabhupada tell us: “So there…, for annihilating, for killing, you require weapon. Krsna has His weapon, sudarsana-cakra. Lord Ramacandra has His weapon, bow and arrow. What is the weapon of Sri Caitanya Mahaprabhu? Sangopangastra-parsadam. His associates are His weapons. This is astra. Because in the Kali-yuga they are so fallen, even they are demons, they are third class, fourth-class demons. (laughter) So they need not be killed. They are already killed. Their mode of life, their atmosphere, they are always dead. Just like we see so many demons. So what is there to kill them? They are already killed. They have no life. So this killing process in Kali-yuga is to kill their demonic propensities. And how to kill that demonic propensities? By spreading Hare Krsna movement. This is astra.”