I read quite a bit about the charismatics gifts back when I first started following God, but I was never satisfied with the explanation of this verse:
“Having gifts that differ according to the grace given to us, let us use them: if prophecy, in proportion to our faith;” Romans 12:6 (ESV)
Most of the teaching I heard around this verse seemed to have some almost “magical” definition of faith behind it. If we prophesy past our “faith bar” it’s not proper prophecy anymore! Of course that’s a parody and caricature, but it still seemed gets at how I viewed this verse. The ESV Study Bible’s note proved a little more helpful, “Paul instructs prophets to speak only when they have confidence that the Spirit is truly revealing something to them, and not to exceed the faith that God has given hem by trying to impress others.”
A thought occurred to me as I read this, what if Paul’s talking about trustworthiness instead of faith? The same Greek word πιστις is used for both concepts. This word plays a big part in the Pastoral epistles, particularly with the formula, “this saying is trustworthy.” Thus, the idea Paul would be communicating is to not prophesy past the trust you’ve established with the community. With itinerant prophets roaming around, this could be a problem.
That said, I’d have to argue for the whole passage being read that way, and look at how exactly Paul uses the word throughout the whole letter. It might be anachronistic to read the Pastoral Epistles back into Romans since they came later. However, this does make more sense of the passage, particularly in the context of Romans 12 and the ethical instruction to the church. Whether it makes sense in context with the whole of Romans is not yet clear to me.
~alex
Alex Poulos, PhD 
Interesting take. I’ve not spent much time on this verse, but your take seems very plausible.
Jason: It’s something I’ll have to go into more detail with later. Ironically, I know Romans less than a lot of the other Pauline books, and I don’t yet have a full enough grasp of it to make a decision. He uses faith, law, works, and spirit in such multi-faceted ways that it’s hard to keep track!