Challenge the concept of natural order, point out flaws in human understanding of it, and criticize the Catholic sexual ethic.
Sure, the natural order could be another way of humans explaining reality, like science, but it is not a sin eater that God must protect with his Justice. It is a system of comprehension that philosophers and theologians made up. Just like science. Our knowledge of nature has never been perfect nor will it be. It develops, like our understanding of homosexuality. Remember, Mr. Natural Order himself, St. Thomas, thought females were flawed male fetuses. Not the case, although homosexuals and members of our asexual priesthood might be, making celibacy an unnatural state as well. The current Catholic sexual ethic is asexuals doing self-preservation.