With the bonus belief I had both religious texts AND itinerant preachers.
I really want to try that again. I have not since maybe King. It is a crazy powerful combination.
I had the whole continent converted to my religion when Isabella showed up. It didn't take long before all I had left of my religion was my own capital. I cannot imagine how I could have been producing more faith or had better wonders and yet she just spammed a never ending stream of prophets, so that whole strategy, which had looked like it was going perfectly, was a big waste.
That would be a very interesting game to revisit, with the benefit of hindsight. I think you could have saved your territory with just a couple of inquisitors, and that would have been enough to re-convert the continent within 50 turns. Of course, capturing a GP is worth a DoW, especially with Izzy on different continent.