I am trying to find scriptural basis on preaching Krishna Consciousness. I understand that in many Bhagavatam purports, Prabhupada cited BG 18:68-71 and Chaitanya charitamrita. However, in the previous verses of BG Ch-18.67, Lord Krishna forbade to preach to non-devotees, without austerity and envious towards Him. Even in 18:68 Lord Krishna tells everyone to preach towards devotee only. Two questions: First, if Krishna consciousness is not preached towards a non-devotee, how can be saved from Maya and become devotee? Second, on what basis then, does ISKCON preach to non-devotees in airport or in the street by Harinam?
I appreciate your responses with scriptural references.