I have used Fear and Faith (and Blades and Heroes) solo, without much success. Some of my post-game notes for an old game sum up what I found (aplogies for quoting myself, seems a bit weird

)
"The combats largely came down to rolling two dice, and didn't seem to catch any of the atmosphere of the situation (e.g. the Hunters had stakes, but other than +1 to fight against Vampires, they're treated the same as any other weapon). I'm all for quick and simple combat, but for most of this I could have just tossed a coin to decide the winner.
More annoyingly, swords and pistol-bows aren't mentioned in the rules at all. I modified this, as it seemed silly for someone with a sword and someone with bare fists (or at most a knife) to be fighting on level terms."
Given that the stats for everyone are very similar and combat comes down to rolling 2 dice, after a couple of rounds it gets very "samey".
There are a couple of nice mechanisms, such as rolling for how many actions you get, with the possibility of losing the rest of your turn if you fail, but combat was a huge letdown.
Chaos in Carpathia is worth a look, and I had more fun with it solo. Mobs, in particular, look promising for adding a bit of randomness to games.