I grew up in the '80s where there's a lot of these kind of post-apocalyptic, post-comet, post-whatever it was, so that always captured my imagination a lot as a little kid, that idea of getting access to secret places and being able to roam around where you're not supposed to.
I write a book over a period of months or years, and when I'm done with it, usually another year goes by before I see it in print. It's hard to be patient and wait.
'God's plan' is often a front for men's plans and a cover for inadequacy, ignorance, and evil.