From Srutakirti Prabhu’s memoir:

I was rubbing his back vigorously and he inquired, “So, we have to accept the sastra. Sastra is our mother. If you want to know who your father is, you have to know from your mother. Is that right?” I immediately agreed.

Then he asked, “What do the scientists say about that?” I was alone and Srila Prabhupada was engaging me in a mock debate. I thought for a moment, not nearly long enough, and responded. “Well Prabhupada, the mother is there, but you have to accept that she is telling you the truth when she says that this person is your father.” Much to my surprise Srila Prabhupada became very upset with me. He shouted, “If you do not accept that is the truth, then what are you doing here? If you do not accept the sastra, then why are you here?” I had no idea what I did wrong. I thought I was playing the devil’s advocate. I quickly confirmed saying, “I accept Prabhupada!” He emphatically said, “Yes, you must accept! If you do not accept you have no business here. This Krsna consciousness is there. We must have faith. If there is no faith, then what are you doing here?”