For full context: http://www3.nhk.or.jp/news/easy/k10011277371000/k10011277371000.html
The sentence in question: そして「これが戦争の結果だ」というローマ法王のメッセージが書いてあります。
My attempt at translation: "Furthermore, the roman popes message is written 'these are fruits of war'."
I've seen this many times in the meantime, but I still can't really explain why 書いてあります is written here. I think the subject of this predicative is not defined, and this is okay, I just wonder why no passive voice is used because this would at least follow the grammar I know xD