This is the sort of scenario I sort of wish was more plausible than it probably is.
My suspicion is that if you managed to get a sort of 'rolling all sixes' result and an actual proper ban on enslaving Christian Africans is enforced by the Pope, you'd see a twin situation of an earlier 'Tippu Tip' sort of situation where somebody goes deeper into the Congo for slave trading, and more of a switch to West Africa.
On the other hand, that still means a large chunk of the Continent is off-limits.
Yes, my thoughts were similar. I think honestly the economic motives are such that an earlier full shift to Benin/Ghana/Nigeria is far more likely than moving past slavery entirely.
But the less optimistic version where the trade from Angola and central Africa is much lower but the overall amount of slaves remains broadly constant would still be hugely significant.
It's also reliant on the continuing existence of a large and stable Catholic Kongolese state. How long does it have to stay up for the ban to stick in a civil war scenario?
But assuming that it does, having such a state stick around would have some interesting cultural ramifications - I'm thinking of the place Abyssinia/Ethiopia has in stuff like Rastafarianism (even if the Rastafaris aren't as likely to exist in a scenario with a much smaller African slave trade).
Well it kind of stuck around in OTL but yes civil wars and foreign conquest meant it had a much reduced authority, this timeline would have to avoid that and that would be significant.
Honestly the culture wars if Christian Africans were increasingly powerful in africa but also purely in the seller and not victim role would be really vicious, and could really push the slaves towards a faith more like vodou and a much grimmer view of the home continent. A lot depends on if Christian converts being free becomes a thing in the new world which is I think a lot harder to get, then them not being sold, especially in the protestant colonies.
Felt the combined sections made this essay flow well. The switch in author voices was not jarring and the actual divergences hit a lot better having the context in which they could have happened laid out.
A better history, but one with a few asterisks since I could easily picture "Thou must not enslave Christians" as just diverting slavers to non-Christian peoples, whether in Africa or elsewhere. Similarly, these indentured service contracts are open to Christians and likely just as open to abuse.
The greatest atrocity has been avoided, but there might easily be dozens of smaller ones in its place. The timeline half full, or at least half fuller.
Also if you look at Islamic Africa, where such laws did exist, they were so often bent and people defined as not muslim to suit. The Mahdists saying they could enslave the turks as they were so heretic as to not be muslims for instance.
I'd suspect similar stuff here.
If I was to write a story in this world, it'd probably be a 'heretic' strain of christianity emerging in the Kongo like the Antonianism that emerged there in 1704 in otl (which among other things claimed that jesus was a black slave) and the argument over whether they counted as christians during the period where the slave trade is dying but not quite yet dead.
One thing I can see being a big thing in this sort of world is 'Pan-Africanism' being seen as somewhere between 'Pan-European' (naïve) idealism and 'Pan Caucasian' 'ooh bit dodgy mate'- as opposed to being a thing that had a wide cultural cachet but couldn't be converted well into a long term project.
Partially because a world where Africa has, presumably, multiple different cultural centres will have less of a 'unite to gain freedom' idea, and partially because there's likely to be some very ingrained rivalries based on who won out in this period.
I think African identity would be so different in this world, it's basically incomparable.