For an example, we'll use the religion ID for Catholicism, which is catholic and the province ID for Paris, which is Knowing those are the two IDs we need, the command to change the religion of Paris France to Catholicism would be. You'll need two things to use this command. This guide will show you how to do the following.
Religion is a big part of Crusader Kings 2, and if you like to use console commands, you'll be glad to hear that there are many ways to modify the religion of characters, provinces and kingdoms with them!