It's sad how many people are using slurs for mental illness in this thread.

What you have here is an example of graphorrhea, the person who wrote it likely has schizophrenia. There is a phenomenon where people with schizophrenia can experience 'delusional meaning making' where they think they have uncovered some kind of truth and urgently need to share it with people. Interestingly many people experiencing this do almost exactly the same thing. This isn't the first time I've seen a post where someone has had a note or a cd covered in scrawlings put through their door! Themes found in these kind of scrawlings often revolve around religion and/or numbers. To the person who wrote it they make sense but that's because they're ill, they don't actually mean anything at all. It's basically just scribble.

No one actually knows for sure why the themes are often maths and religion but it's quite interesting Imo. Perhaps the parts of the brain that deal with these things are activated when people have these episodes.

You don't need to be worried though. It doesn't mean anything and you're not being targeted. They've very likely made multiple and shared them elsewhere too.