The Mogen David actually doesn't have that long a history as a Jewish symbol; the earliest associations are back in the 11th century and even then it was perhaps most often associated with the Kaballah.
Absolutely and even today some Jews do not like it's usage as a recognised symbol for Judaism. As to the thread's topic as Paisius says it does indeed have the ring of conspiracy theory. What's better yet is the fact that like all the best conspiracy theories it's managed to combine as many groups as possible under one heading as can be.
...and like with all 'conspiracy' theories, in order to be a true believer you have to suspend logic and accept the fact that tens, if not hundreds, of thousands of people will be 'mum' about the 'conspiracy' for years, decades and centuries. Since drink, money and sex will usually ferret out even the darkest and deepest of secrets if applied properly, I don't find such 'theories' to be anything but nonsense.
Oh, and by the way, the Russian Orthodox Church must 'in' on this as well. Have you ever noticed that the hexagram is often used as a emblem on Russian phelons? Hmmm....
You know there seems to be a kind of small minority of members of both the Catholic and Orthodox Churches who love the whole 'world been run by international Jewry' stuff. There must be something universally appealing about this er stuff. At the moment outside this site I'm caught up in a debate where some Catholic guy is trying to use a site by a purported Orthodox monastic to show me how the Protocols of the Elder of Zion are true and a great fount of wisdom. The fact that I've pointed out that the guy he is using as a source belongs to monastery that is in schism with ROCOR and has been condemned by them makes not the slighest difference to the whole exchange.
To my mind, conspiracy theories are one of Satan's greatest inventions.
They play on the minds of people. Like true religious faith, they require one to accept much which appears to be irrational and contradictory and unseen. They are a great tool for those who would use 'reason' and 'logic' to destroy faith, for if the believer in a conspiracy theory finds his or her belief in the conspiracy to be foolish, they may be susceptible to having their religious faith undermined at the same time - or they may never find the means to gain such faith.
Likewise for those antagonistic to religion, they lump the pious Christian in the same boat of illogic with the conspiracy theorists, making it easier for them to dispense their own doctrines of non-belief.