I had asked you a question ("Decided by whom?") about what you had said, and you did not answer my question. You reacted to the question I had asked you in a manner as though you thought I had not really asked you a question, but rather, had said something for you to express agreement with ("Exactly.")
I definitely would never say any nonsense like "All devout truths are relative. There's no one exclusive claim to their veracity." So, forgive me for disappointing you, but you're mistaken if you thought you and I were in agreement about something.
I was really asking you about whom you were talking about when you said, regarding a proposed debate, "And how would the 'winner' be decided?" For, every deciding--every decision--belongs to some person: no person, no decision. So, I was essentially asking you to (so to speak) fill in the blank with the name, or description, of some person, or party of persons:
Did you mean, "And how would the 'winner' be decided by those who, on the point up for debate, agree with quip?", or did you mean, "And how would the 'winner' be decided by those who, on the point up for debate, oppose quip?" Which?