I was researching the life of Charles II, when I came across an interesting item on Wikipedia:
There is a theory that the term took on its present meaning from a group of ministers formed in 1668 – the “Cabal ministry” of King Charles II of England. Members included Sir Thomas Clifford, Lord Arlington, the Duke of Buckingham, Lord Ashley, and Lord Lauderdale, whose initial letters coincidentally spelled CABAL, and who were the signatories of the Secret Treaty of Dover that allied England to France in a prospective war against the Netherlands. The theory that the word originated as an acronym from the names of the group of ministers is a folk etymology, although the coincidence was noted at the time and could possibly have popularized its use.
In those days, secrets were part of Jewish mysticism and the term Cabal, which derived from Kabbalah (also spelled Cabala), meant anything that implied a ‘behind-the-scenes’ manipulation of events.
David Wilcock uses the term a lot.