The sentence is:
Admittedly, for every lost prophet there is a crank who is simply lost.
This is from an article in The Economist, here: http://www.economist.com/node/21542193
I gather from the context that the sentence means to say at least that the participants of online forums are varied: There are intelligent people and there are cranks who don't know what they are talking about but insist on pushing their ideas. And, using two instances of lost is clearly a clever thing which The Economist is known for. But the meaning of lost prophet in general and in particular for this context is, well, lost on me. I Googled and found that Lost Prophet is at least the name of a book, so using these two words together clearly isn't a first the news weekly. My guesses are:
a) a prophet who's prophecy is "lost" on others; the prophet is ignored, not heeded;
b) a prophet who was lost (= unknown, unreachable) to the world but re-found and greatly appreciated on the online forum for his/her words;
c) a prophet who lost on one of his/her economic predictions, having made a bad prediction.
Any input would be appreciated.