Welcome to Plague is a document in Outlast 2.
It is located next to a dead body laying by a small stream leading up to the Scalled villages in The Scalled.
"THIS FUCKWORM MISTOOK HIS BLESSINGS FOR SICKNESS AND TRIED TO LEAVE AND I BROKE HIM. DO NOT MAKE HIS MISTAKES OR COMMIT HIS SINS. GOD AND HIS PROPHET LOVE YOU."