The Kabbalah is not an "institution" like Freemasonry, you can not "join" Kabbalah, Kabbalah is a set of belief, ideology and practices for spiritual development, and yes it is practiced by many institutions, groups, orders, people etc. There is nothing "satanic" about it, and yes it may be the "Fruit of Knowledge" as the Tree of Life relates to the Kabbalah.
Kabbalah:
http://en.wikipedia.org/wiki/Kabbalah
Tree of Life, in different cultures:
http://en.wikipedia.org/wiki/Tree_of_life
10 Sephiras and 22 paths of Kabbalah / tree of life:
http://en.wikipedia.org/wiki/Sephirot
Marjor Arcana of Tarot, the 22 cards:
http://en.wikipedia.org/wiki/Major_arcana
AMA-GI: I agree to your post though personally I see two different main sides of satanism, the one submitting themselves to a Satan deity, and those who do not consider Satan a deity. There are many branches of these two main sides. Some of them do involve themselves with darker arts, sacrifices, devil worshipping etc, while others do not and have a completely different view on things.
However, Satan, has by time been charged with huge amounts of negative energy, even as a word, and from my experience this have manifested itself as a collective thought form that one can consider a Satan-deity.
Thoughtforms:
http://en.wikipedia.org/wiki/Thoughtforms
The same goes for all other deities, gods, demons, angels, entities etc throughout history and the different religions.
Blessings, and may the inner guide be with you
-EA