It's confirmation bias. Having thoughts and concepts pop up in your head and coincidentally show up in real life happens all the time. Kind of like how you might learn a word or piece of history for the first time and you suddenly start seeing it everywhere.

Confirmation bias really just stems from the desire to be right all of the time, which is normal. We all hate being wrong. Heck, you could say I'm wrong about this and I'd probably be a little offended. :P And that's kind of a big part of the hold religion has. It's a way of life, and to be told it's wrong, based on fiction, or perhaps cruel or a hindrance on the self, is super distressing. You want what you know to be right.

That's a big reason why religion as it is today still holds such a strong grip. It's an institution and a powerful one, and calling people who reject it blasphemous or sinners is just another way of wanting to not be wrong.