Here is another example for you. I am an artist and people interpret my works in VERY different ways, what they interpret is true to them, it is their feeling. I can tell them they are wrong but that is just my opinion even though I created the art. We are all entitled to what we believe. I think fact and feeling are two different things and religion is one of the few places they attempt to coexist. Which is why we must respect each others feelings about a topic even if they are different from our own. Each of us has unique life experiences and physical bodies that lead us to perceive the same thing differently. Even in science I might say "That is one inch of thread, without doubt!" and someone else will say "NO, absolutely not! That is definitely 2.54 centimeters of thread!"
We can try to educate others and tell them our view but it is ultimately their choice, their path, and we must respect it.
So if a person says the sky is green, perhaps where they come from blue is called green, or perhaps they are colorblind, or for whatever reason they see green there is usually a reason. If they are telling what they believe to be the truth then they are experiencing it as green, so to them it is truly green. AND if they can convince enough people then yes, it will be green!
The diet example is comparing faith to science, you cannot measure one with the other, its like trying to describe the sound of a color. BUT some people need more iron, some cant digest milk, some are allergic to nuts. No one diet is perfect for everyone, we all have different physical, emotional and spiritual needs. I think religion is no different.
-Peter Ochabski