I came across the expression the writing is on the wall in a translation about the environment explaining that climate change and all its horrid consequences are inevitable. I immediately thought of the translation: C’est écrit (It is written, and I’m still humming Francis Cabrel’s song, by the way, which is quite annoying). The English expression come from an episode in the Bible:
Daniel 5:5

Belshazzar the king made a great feast to a thousand of his lords, and drank wine before the thousand. Belshazzar, while he tasted the wine, commanded to bring the golden and silver vessels which Nebuchadnezzar his father had taken out of the temple which was in Jerusalem; that the king and his lords, his wives and his concubines, might drink therefrom. Then they brought the golden vessels that were taken out of the temple of the house of God which was at Jerusalem; and the king and his lords, his wives and his concubines, drank from them. They drank wine, and praised the gods of gold, and of silver, of brass, of iron, of wood, and of stone. In the same hour came forth the fingers of a man’s hand, and wrote over against the candlestick upon the plaster of the wall of the king’s palace: and the king saw the part of the hand that wrote. Then the king’s countenance was changed in him, and his thoughts troubled him; and the joints of his loins were loosed, and his knees smote one against another.

God isn’t happy with Belshazzar and his guests’ defying him and behaving in such a licentious manner, and sends them an omen: Babylon will fall. I’m not sure whether the French expression has the same origin or whether it’s been borrowed (under a shorter form) from English. Its meaning differs slightly from the English expression: where the writing is on the wall announces an inevitable catastrophe, c’est écrit indicates an inevitable event, which could be positive (ex: "she will get a promotion, c’est écrit"). In my document, the writing is on the wall was immediately followed by a catalogue of all the problems we are going to face, so I thought the neutral aspect of c’est écrit wasn’t a problem: the text made it clear that our fate is indeed a frightening one.