This is one of the first Economic Policies designed to boost a specific stat (File:Civ6Faith.png Faith in this case) other than File:Civ6Gold.png Gold or File:Civ6Production.png Production. It works by doubling Adjacency bonuses of a District; this means that first, you have to have such District, and second, it has to have Adjacency bonuses, if you are to make use of Scripture. What's more, districts which have higher native Adjacency bonuses will benefit more from this Policy than ones with low bonuses.