I've given this (too) much thought and I'd simply kill the Paladin class as it is today/in BG3.
It started off as a CLERIC then drifted into a Chivalric KNIGHT - thus both Lawfull and Good. Then it started drifting even more, into Divine Enforcer territory ... and into the mess it is in 5ed, with Oath, no Divine angle, yet with legacy mumbo-jumbo about Good even though Allignments for Paladins were ditched.
Hence in BG3 I'd axe the Class as such, instead adding it as Subclass of Fighter at 3rd lvl. The Oathbound Knight. A warrior abiding by a CODE.
Channel Oath charges are used for Smiting (not called Divine anymore, but Righteous or something like that), Lay On Hands becomes Help as Extra Action (they are skilled in battlefield first aid :P), and no Divine Magic Spells.
This eliminates the messy religious angle. They are OATHBOUND KNIGHTS. And lose their Smites if they do not abide to their
bushido 
Devotion - for the classic feel, LG
Ancients - LN, I'd guess
Vengeance (can use mechanics of Larian's Oathbreaker) - LE
On the other hand I'd like to see implementation of Oath Breaking for Clerics - e.g. if a Priest of Melikki kills the Owlbear Cub, Priestess of Lollth kissy-kissy with Astarion
ewww, a SURFACE ELF?!? wot u thinking gurl?!?, Shaman(ess) of Gruumsh aiding weaking Tieflings against the
go-getter upwardly mobile Absolutist Gobbos - then bye-bye Spells until Atonement.
