No need to continue in your perplexity. As I told MA when she first joined the board, if you want to sharpen your rhetorical skills, you should practice on unbelievers. Consider this ancient advice:
Solomon wrote: By iron, iron itself is sharpened. So one man sharpens the face of another. (Proverbs 27:17)
As for kefir, I find it tastes much like a yogurt milkshake.