Simply eating other people doesn't really require any specific abilities... So, bon apetit!
Of course. This is pathfinder, everything is possible.
In some faiths, this “eating” is a purely symbolic act, while in others, the inquisitor must eat a small amount of food and water as part of the ritual. A few extreme faiths actually require the inquisitor to eat some of the body of the slain enemy.
For 'flavor' (heh), you might want to pick up the Corpse Cannibal religion trait.
Notable cannibalism-themed options:
Witch Major Hex: Cook People
Gingerbread Witch Archetype
Deities: Kabriri (with an appropriate Demonic Obedience), Zura (also with a solid Demonic Obedience), Pavnuri (weak Obedience), and of course, Urgathoa (with of course good Deific Obedience options).
Hmm...any faiths that encourage this?
Gulthor mentioned a couple good ones, all evil.
But if we try to contextualize the eating as something morally acceptable instead of evil, we can follow neutral and even good deities.
Imagine that you are a hunter who strongly believes that the act of killing a sentient creature is detestable, even evil.
You've been told from a young age that a hunter isn't a murderer only because they hunt from need. The hunter honors their prey by consuming it, allowing the strength of their prey to become their own.
That same hunter was now faced with a situation of life or death, where they killed a man to survive. From the hunter's point of view, it would be an evil act to not eat from their opponent, since that would mean their death had no purpose.
If you played a character like this, you could probably worship any of the deities with 'Hunting' in their areas of concern. So I'd argue that you can worship Ketephys, Neith, Skode, Uskyeria or Erastil.
Remember that you can belong to a group of followers that has an extreme interpretation of their god's message.
In addition to Sin Eater, another mechanical option I like is the
While your actual dietary needs don’t change, you crave the flesh of sentient creatures. You can only go without food for 12 hours before you begin to starve, and when you do starve, the DC of the Constitution check to avoid taking damage increases by 5. If you feed on fresh, raw flesh (no older than 1 hour) from a creature of your own race, you gain a +1 morale bonus on all saving throws for 24 hours. At 5th level, you add ghoul touch to your list of 2nd-level oracle spells known. At 10th level, you become immune to paralysis and disease. At 15th level, you gain the effects of heroes’ feast whenever you feed on the raw flesh of a sentient creature, and the effects of this heroes’ feast double if the flesh you eat comes from a member of your own race (this effect applies no more often than once per day).
I've added this to a character via VMC (which also granted me a mystery).