hmm..
What about a cult of paladins?
A secret cult, known to only a few; known as the Knights of the Raven, they each bear a piece of raven jewellery. Small, so as not to interfere with their surcoat of arms, but there.
The Knights of the Raven follow the path of the Book of Ashes, a book that was rejected from the main body of literature of the church due to its extremist nature. It is a book of prophecy, portraying the eventual demise of the Church and the destruction of all that is good, until '..Ravens, were to pick the dead things from the living body of the church, until it will heal again..' While not embraced by the church, it was witnessed that the prophet performed several miracles and was possessed and in the company of Angels at many times.
The knights of the raven are a political/religious cult, but one that is based around the writings of a prophet that while loosely respected isn't one of the major parts of the church. They routinely follow the religious rites as dictated by the prophet, which could be innocent or evil, and seek in the often incoherent ramblings of their Book of Ashes. Mainly concerned with dealing with corruption in the church and in towns they are near, the group uses its groups of seers and prophets to get their next strike. Using their knowledge of the dark future, they seek to prevent it by dealing with those who threaten the world.
They are completely sworn to ending evil wherever it may lie, and as their religious group gained converts have become more than just a chapter of Knights with an extremist view on how to combat evil. Now, the knights use military precision, different skills of individuals, as well as their original brute force to crush any possible problems that are facing the church. The 'Brother' knights are still the political center of the cult, but 'laymen' with skills such as sneaking around, picking locks, or any other profession will be used.
Also, as funds were needed by the knights for their evil-hunting expeditions, payments from certain smaller evils such as brothels and taverns selling darker forms of drugs began to be more appealing, and so on.