Srila Prabhupada extensively preached that one can be Guru If They Know the Science of Krishna.
Room Conversation—January 31, 1977, Bhuvanesvara:
“Are you knowing people take diksa from many gurus?”
“No, diksa-guru is one. But siksa-guru can be many.”
“But suppose diksa gurus or people take one mantra from one guru and other one…”
“Then you have not selected guru. You have selected some rascal. Guru can be…, cannot be different. Guru means one who knows the science of Krishna. Yei Krishna-tattva-vetta sei guru haya [Cc. Madhya 8.128]. Anyone who knows the science… So, suppose if you want to become medical man, you must go to a qualified medical man to learn. And if you go to a panwala, what he’ll teach you? That is your mistake. Guru cannot be different. Guru is one, one who knows the science of Krishna. If he does not know, then he is not guru. Why should you go there?”
“How should we know that he knows about Krishna?”
“That requires your fortune. Little intelligence. Therefore, Caitanya Mahaprabhu says, ei rupe brahmanda bhramite kona bhagyavan jiva [Cc. Madhya 19.151]. That intelligence is for the most fortunate person. That is not ordinary thing. But guru means who knows the science of Krishna. If you go to a bogus man, that is your misfortune. So, this is the description of guru, yei krishna-tattva-vetta sei guru haya, Caitanya Mahaprabhu’s statement. [Cc. Madhya 8.128]
‘It does not matter whether he is a sannyasi or grhastha or a brahmana or sudra. It does not matter. If he knows the science of Krishna, then he remains guru.’”
“Science of Krishna. If he knows about Bhagavatam, Bhagavad-gita, or anything else…”
“To know about Krishna. It is not also difficult. Science of Krishna is there, Bhagavad-gita. Krishna speaks Himself. So, to know the science of Krishna is also not difficult. But because we are unfortunate, we go to rascal, and they interpret Bhagavad-gita in a rascaldom way, and we are missing. So, you should be very careful not to go to a rascal. Then your mission will be successful. If you want to purchase gold, you must go to a shop where actually gold is purchased, gold. If you do not know, then you’ll be cheated. That is not also very difficult. That I have repeatedly said. Those who are interpreting in their own way, Bhagavad-gita, he’s a rascal; he’s not guru. As soon as he says an interpretation, ‘I think like this,’ you reject that. Why should we think like that? You should preach what Krishna says. Then you are right. Why should you say something which Krishna does not say? Then you are misguided. He does not know Krishna. He’s not krishna-tattva-vetta. So, he’s cheating. That is going on. Krishna says, sarva-dharman parityajya mam ekam saranam vraja [Bhagavad-gita18.66], and these rascals say, ‘It is not to Krishna person.’ So, he’s a rascal. He’s taking Krishna’s book and preaching against it. So, what will be benefit if you go to such a rascal? Therefore, there is no difference between siksa-guru and diksa-guru because if he’s actually guru, he’ll not say anything which Krishna has not spoken. So, guru is that. Caitanya Mahaprabhu says, [Cc. Madhya 7.128] ‘You become a guru’ And what is the function of the guru? That is there. You haven’t got to manufacture any instruction. Whatever is said in the Bhagavad-gita, you say. You try to convince him with logic, with philosophy, with your knowledge, same thing, not philosophy. That is intelligence. And suppose Krishna says, Bhagavad-gita. 18.66,
“Abandon all varieties of religion and just surrender unto Me. I shall deliver you from all sinful reactions. Do not fear.”
Before that, Krishna has described everything, why you should surrender to Krishna. At last, He says, ‘You surrender to Me.’ So, there is no difficulty. Immediately Krishna does not say, ‘you surrender to Me.’ But after describing everything—karma-yoga, jnana-yoga, dhyana-yoga, so many things, politics, sociology, religion, everything—at last He says that ‘This is the most confidential part. You surrender unto Me. So, one who has not surrendered to Krishna, how he can become guru? He’s a cheater.