One of the major events of the modern history was the Christianization of Sub-Sahara Africa, with places like Nigeria, South Africa, and the Democratic Republic of the Congo becoming missionary hotbeds, often replacing traditional tribal faiths. The collapse of the modern world left the continent in an interesting place. It is very, very rare for widespread polytheism to return, even after the fall of empires. However, the collapse of industry meant a collapse in infrastracture--many of the Churches, already decentralized could not be maintained without Western backing. The Catholic Church fared little better, being relatively new, and having to deal with the wall of Muslim occupation in North Africa. Africans were still believers in Christ, but the sense of insitutional community was imperied.
This is where the Ethiopian Church stepped in.
Ethiopian Orthodox Tewahedo Church is one of the longest continuous religious bodies in the world, being integrated with the Ethiopian Church for half a century before Rome officially adopted Christianity. A longstanding and Indiginous lineage few others possess. In the New Middles Ages is has an expnasive, if not always dense, presence in Sub-Saharan Africa.
Ethiopia also has a sense of legitimacy in a post-colonial world very few places can top. It evaded colonial subjugation, only briefly being conquered during the second World War. Africa considered a truly aspirational place, and Pan African movements conjectured that any ceremony uniting the continent should be held there. It squares for a populace that wishes to remain "saved" but throw off the yokes of invading empires. Aksum is closer to Rome, more organized than any Protestant mission, and is truly, intrinsically African.
In the new Middle Ages, the Tewahedo Church has absorbed various missions and religious centers. Most decently sized towns possess at least one Bete (Church), and are either hewn into rock, or concentric "hut" buildings as as geography allowed. Gedans, or monasteries, are usually found in the deserts and mountains of the continent. The Church can't afford to really micromanage, and in general the religious structures are more akin to Buddhist priests and temples than historical Christendom. The important thing is that villagers come to them, that message can be found and that the word is available in as many corners of Africa as possible. Ehtiopian Church is as a result highly syncretic.
Aksum also wants to make certain its influence by positioning itself as the sort Ivy League of Africa, inviting the great empires and kingdoms to send their princes there to get an education. This keeps the continent interconnected to some degree, and also means that its traditions in writing, architecture and fashion leaves footprints, even if just in the more elite circles.
