Ah, but it's not true. Non-fiction is certainly useful, just like a history textbook is useful, but it doesn't have the power of story.
Let's start with geography. I'm pretty good at it, but even I have trouble finding most countries in Africa. I can find Egypt, Libya, Madagascar, South Africa, and maybe Ethiopia and Somalia, but the other 48 countries are harder to pin down. I think most Americans are the same. Why? Well think about the countries you know. I know Egypt from the Bible (among other things). I know Madagascar because its the only island nation and I've seen the movie. I know Libya and Somalia because we've fought wars there.
And I know Tunisia because of Star Wars.
I know where these countries are because I have stories--even dumb ones--associated with them in my mind. No matter how many times I've memorized African geography (and I have), the only nations that stick over time are the ones for which I've learned a story.
Another example: I've been to church my whole life, but I'd have a hard time telling you the content of most sermons. Not because I didn't listen, but because they didn't stick. I do, however, remember stories. Like when my pastor went fishing without a line "so the fish wouldn't bother him." Or the story of the bridge raiser who sacrificed his son to save the people on the bridge.
Stories stick, even fiction. I have trouble remembering the details of C.S. Lewis' Mere Christianity, but I will always remember the moment in Voyage of the Dawn Treader when Eustace needed Aslan's help to shed the dragon skin he could not.
We DO write fiction to entertain, but I hope the stories I write also have meaning for those who read them. Because those stories--meaningful or not--will stick in their minds a lot longer than most non-fiction.
What stories mean something to you?