Excessive detail for tabletop fans
The story of the Sabbat across the editions is actually really fascinating—starting out as the most monstrous and evil antagonists possible, then turning into a group of extremists who make some valid points because people saw Vicissitude and Obtenebration and said “we want to play this now”. Fifth edition wanted to send them back to their roots, so some metaplot events have decapitated their old hierarchy and the organization splintered under the strain; the ones who call themselves “Sabbat” now are mostly the unrepentant monsters again. (The short version is, turns out “we don’t care if the humans know, we’re better than them” is a terrible idea in the modern surveillance state…especially when you refuse to consider allying with any of the other factions.)
Maria’s “Church of Caine” is one of those splinter factions; she saw the Sabbat who were more interested in monstrosity than subtlety get hunted down and eradicated by human hunters and vampire factions alike. So when she suddenly had the freedom to define things her own way, she tried to find a way to make her religious views palatable to the other factions and avoid getting run out of town with torches and pitchforks. (She specifically avoids calling herself “Sabbat” for this reason.)
They (the Church) were introduced in one of the more recent tabletop books and I like them as an additional faction that can coexist with the Camarilla and Anarchs. But, well…Maria’s still on the Path of Power and the Inner Voice, and is more than happy to eat someone’s soul if she thinks he betrayed her ideals. So there’s a reason getting her on your side will always without exception turn another faction completely against you.