The Cult Sanguinary is believed to be a defunct offshoot of the clergy of Cuthbert. The official Clergy of Cuthbert has historically preferred not to comment on the Cult, letting them fade into obscurity. The establishment of a new temple will certainly cause some issues within the clergy, it is unclear how they will proceed.
The last surviving member of the Cult Sanguine was Sir Julin of Wallenby, a distant relative of the last Baron of Wallenby. Always a small sect, the temple dwindled along with the rest of the barony, acolytes, priests, and knights dying one by one of age or misfortune. When the last of his flock passed away, he entombed himself in the mausoleum with the bravest of his dead brothers, and vowed to watch over them through the ages. It is said that he sealed himself without his iconic blood-red greatsword, "Red Ruin". No one knows if this is true, or where the sword may have ended up, if not at rest with Julin.
Some religious historians postulate that the Cult Sanguinary in facts worships a demonic force masquerading as an aspect of Cuthbert.
Sanguinary Paladins must take the oath of vengeance at level 3. In addition, they lose their Abjure Enemy channel divinity power. It is replaced with a new channel divinity power called Sanguine Siphon.
Sanguine Siphon Channel Divinity power: Once activated, for the next minute (6 rounds) one quarter of all weapon damage dealt by the paladin is returned as health. Damage not caused by a weapon does not activate this healing, but spells and effects that work on the paladin's weapons do. The paladin cannot use this power to go over his hit point limit, but the hit points do not go away and the end of the minute.
Cult Sanguine paladins must do one point of damage with a weapon to an enemy, a church member, or themselves during each long rest, or within an hour of the rest ending. They may inflict this point of damage upon themselves. It may be healed however they wish, but it must be inflicted. Failure to do so results in the paladin losing all paladin powers until after the next long rest (as long as he takes or inflicts one point of damage at that time)