The Bishop goes on to the human eye, asking rhetorically, and with the implication that there is no answer, 'How could an organ so complex evolve?' This is not an argument, it is simply an affirmation of incredulity.
I remember when I was working on Mission: Impossible 2, John Woo said, "In Hong Kong, there's not much money and a lot of time. In Hollywood, a lot of money, not much time. " Personally I'd prefer not much money, a lot of time.