You probably didn't mean that: the difference between fact and fiction doesn't depend on anyone's senses and beliefs, but on what the world is as a whole.
What we think is fact or fiction will depend on our senses and beliefs.
Basically, even a genuine belief in in unicorns and pixie dust don't make those a fact. It's fiction, the believer just doesn't know it.
As for religion and secularity… well, either there is a God, or there isn't. If there is, secularity won't make it go away. If there isn't, religion won't make it true.
The important is to accept we are wrong when evidence arises, and change our mental model.
I was never sure how to deal with this postmodernist crap. When someone deliberately confuses the map and the territory, what can I say?
Let us just observe that sometimes, I believe something, and then, I see something else happen. That tend to give me a sense that something is going on outside of my mind. http://yudkowsky.net/rational/the-simple-truth
This generalizes to the entire humanity, by the way. Most people believed in a Young Earth, then we discovered fossils. Most people used to think the Earth was the centre of the universe, then Copernicus, Kepler, and Newton, proved otherwise.
> The important is to accept we are wrong when evidence arises, and change our mental model.
That I must agree with. On the other hand, I'm not sure how this can help those who believe in magical thinking.
Hit them with a rock. Objective reality hurts.