It is a faith not in good, but in evil.
Kennedy politics had been meant to be optimistic, but the assassination accelerated the liberal reversion to the underlying pessimism and paranoia, the sense that life was doomed, that people had to be rigidly controlled to keep society from coming apart.
The assassination was a warning, not from some secret organization, but from the consequences of the ideas of the left. Instead of searching for Cubans in the CIA, liberals should have looked in the mirror instead. The chaos and violence they were afraid of was not coming from some secret organization, it was coming from inside the movements of the left.
It still is. 
The real Kennedy conspiracy was an effort to suppress the basic truths of what had happened and to replace them with a recursive loop of conspiracy theories that could never resolve anything while convincing everyone that the basic truths of what happened could be safely ignored.
The conspiracy did not cover up the work of the secret organization that killed JFK, but the secret organizations of the left whose ideas led to his murder. The real JFK conspiracy concealed the deeper secret that the left is destructive and that its ideas carry a dark wind of chaos and violence.
The left cannot make history come out the way that it wants to, but it can always lie about it. Its myths of the past, dreams shattered by vast right-wing conspiracies, swallowed up by the greed of the 80s and 00s, are tawdry attempts at refusing to learn the lessons of history so that it will be given the freedom to repeat its terrible mistakes.
Lee Harvey Oswald was the stepchild of the left’s destructive ideas on society. The same madness that led to Guyana and the bombing of the Pentagon had its day fifty years ago in Dallas.