FROM WHERE WE SHOULD GET THE KNOWLEDGE ABOUT KRISHNA? 

One should get knowledge about Krishna  from Krishna Himself and His authorized representatives thru bonafide Guru parampara.

SRILA PRABHUPADA SAYS:

“We have to take knowledge from Krsna. We shouldn't accept any process of gaining knowledge except hearing from Krsna or His representative. Then we will  have first-class knowledge. 

If you find an authority who is representing Krsna and who can speak on the subject matter, and if you accept the knowledge he gives, then your knowledge is perfect. Of all the processes for  receiving knowledge, the least reliable is direct sense perception. 

Suppose someone asks, "Can you show me God?".  That means he wants to experience everything directly.  But this is a second-class process for gaining knowledge, because our senses are imperfect and we are prone to make mistakes. 

Suppose you need some gold but you don't know where to purchase it.  So you go to a proprietor of a hardware store and ask, "Do you have any gold in stock?" He will immediately understand that you are a first-class fool because you have come to purchase gold in a hardware store. Therefore he will try to cheat you. He will give you a piece of iron and say, "Here is gold." Then what will you say? Will you accept that iron as gold?

Because you do not know what gold is, and  have gone to a hardware store to purchase it, you will get a piece of iron and be cheated.  Similarly, rascals who demand that they be shown God do not know what God is, and therefore they are being cheated by so many bogus spiritual leaders who claim that they are God.  That is happening.”.