You can take it for granted that nondevotee class who is not in Krishna Conciousness as we are teaching are all great fools never mind how ever they may advertise themselves as meditators, yogis, philosophers, religionists, and so on. We are presenting a scientific program of God Conciousness on the basis of the highest authority, Bhagavad-gita. For a preacher there are four principles to be followed. One, he must be fully surrendered to Krishna. Two, intimately in friendly relationship with devotees trying to elevate conditioned living entities to Krishna Conciousness and rejecting the nondevotee class. So if you find a nondevotee eager to listen submissively you can show your mercy to elevate him to Krishna Conciousness, but a nondevotee who is already poisoned by the serpent of the demon class swami or yogi is very difficult to be dealt with, so the best thing is to reject them and not waste time for their elevation; but a person who is willing to hear us submissively must be given chance to understand the philosophy of Krishna Conciousness. I am very much obliged to you for expressing your good sentiments on account of my humble service to you all. Your appreciation of my humble service is thankfully accepted.

From Srila Prabhupada’s letter to Gurudasa — Los Angeles, 24 February, 1968