If it's possible at all, it's a serious challenge.

Basically, the Religions table has a single true/false field for "Requires Custom Name". If true, you must enter a custom name and AI players can't choose it. If false, AI players can choose it but there's a preset name you can't change. You obviously have to have enough of the latter to cover all the AI-founded religions, or things break.

To change this paradigm, and allow a custom name for religions that have a default name already, you'd have to introduce an entirely new capability to the game. That's hard, if it's possible at all.

Introducing new logos for custom religions? That's easy, and that's why it's been done so many times already. You wouldn't want to clone the historic religions exactly because of possible confusion, but otherwise that's just a matter of creating new icons and adding to the table.

Thank you very much, I had no idea it was baked so deeply into the game, all they would have had to do would be to give all the starting religions default names (which is I guess how it used to work) and have a random name list at lest as long as there are extra logos to name. I'm surprised they would set it up in such a way after having a way that works for everyone for 5 games in a row.

Thank you for taking the time to answer my question!