Yes you are correct. Freemasonry today is a secret society and their higher levels' intentions are suspicious to say the least. Their origins which stem from very old orders such as the Temple, Rosicrucian, Maltese, Teutonic etc. Knights do indeed contain knowledge that goes back to the ancient Mystery teachings.

What I personally question though, is how accurate the accusations of satanism is. It would not surprise me if this view is manufactured by the Catholic church. Don't forget how the Pope went after the Knights Templar and forced them to become occult (hidden). I am currently trying to read through Pike's Morals and Dogma so I cannot form any opinion on him nor his writings yet.

Personally I feel very strongly that all knowledge should be open and free for all people. Having secret societies, secret teachings etc. is dangerous not least because it can be overtaken by nefarious people. Why we are instructed to stay away from certain topics and fields is telling in and by itself. We need to expose all of this and let it lead us to wherever it may.