Hi,

In this quick guide will show you how to quickly get the achievement mentioned in title which can be done by latest 1450 - 1455 depends on what allies get Mahra. The main objective here is to take one of Mahra coptic province and then convert to coptic, which counts as converting to christian.

Usually Mahra does not get strong allies and can be easily taken down with a few loans and obtaining a good ally yourself in that region. I took Hormuz, as someone on reddit said is the most likely country to join (and it was).

1. Taking Socorta

After you get the ally, no CB Mahra, call Hormuz in the war (promising them land). Your main target will be Socorta (the island near Horn Cape) which will be used to convert. However, first focus on taking out their ally as you wont have to worry later for besieging and will get a higher tick score. By then, Hormuz is likely to peace out or not worry too much about the conflict. Don't worry thou, Mahra alone is easy to be taken down. Therefore, use your boats to move 1-2K army in Socorta and rest of them to occupy whats left of territories in Arab peninsula. Demand in peace deal Socorta and make it a core.

2. Converting to Coptic

Following coring Socorta, make the new province your capital so that rebels will break it quicker. Create unrest for religion converting of the area and let them have fun but pay attention as is possible you get first independence rebels which are not the same!
You have two options which will end in breaking your own country. You either sell mainland provinces so that rebels quickly finish converting or just wait for them to move around until they break it. I went it first as wanted to finish quickly and was not interested in do, at that time, a full Sindh run.

3. Some ways to create religion unrest

A. If separatists appear first, you can use harsh treatment to make them go under 30%. Usually helps switching to other form of unrest.

B. Lower autonomy in the province

or if you go further with the campaign, get more coptic provinces and relgious rebels will show up.

Thank you and have fun :)