The Mayavadis and other atheists do not want the Krsna consciousness movement to develop because it educates people in God consciousness. Such is the policy of the atheists. There is no benefit in feeding a snake milk and bananas because the snake will never be satisfied. On the contrary, by taking milk and bananas the snake simply becomes more poisonous (kevalam visa-vardhanam). If a snake is given milk to drink, its poison simply increases. For a similar reason, we should not disclose our minds to the serpent Mayavadis and karmis. Such disclosures will never help. It is best to avoid association with them completely and never ask them about anything confidential because they cannot give good advice. Nor should we extend invitations to Mayavadis and atheists nor accept their invitations, for by such intimate intermingling we may become affected by their atheistic mentality (sangat sanjayate kamah). It is the negative injunction of this verse that we should refrain from giving anything to or accepting anything from the Mayavadis and atheists. Sri Caitanya Mahaprabhu has also warned, visayira anna khaile dusta haya mana: [Cc. Antya 6.278] “By eating food prepared by worldly people, one s mind becomes wicked. Unless one is very advanced, he is unable to utilize everyone’s contribution to further the Krsna consciousness movement; therefore on principle one should not accept charity from the Mayavadis or atheists. Indeed, Sri Caitanya Mahaprabhu has forbidden devotees to associate even with ordinary men who are too addicted to material sense gratification.
The Nectar of Instruction, Text 4, purport