Whenever God incarnates He has two missions, as stated in the Bhagavad-gita. There Krsna says, “Whenever I appear, My mission is to deliver the pious devotees and to annihilate the demons.” When Krsna appeared, He had to kill many demons. If we see a picture of Visnu we will notice that He has a conchshell, lotus flower, club, and disc. These last two items are meant for killing demons. Within this world there are two classes of men-the demons and the devotees. The devotees are called demigods; they are almost like God because they have godly qualities. Those who are devotees are called godly persons, and those who are nondevotees, atheists, are called demons. So Krsna, or God, comes with two missions: to give protection to the devotees and to destroy the demons. In this age Caitanya Mahaprabhu’s mission is also like that: to deliver the devotees and annihilate the nondevotees, the demons. But in this age He has a different weapon. That weapon is not a club or disc or lethal weapon-His weapon is the sankirtana movement. He killed the demoniac mentality of the people by introducing the sankirtana movement. That is the specific significance of Lord Caitanya. In this age people are already killing themselves. They have discovered atomic weapons with which to kill themselves, so there is no need for God to kill them. But He appeared to kill their demoniac mentality. That is possible by this Krsna consciousness movement.

From The Science of Self-Realization by Srila Prabhupada