We found 2 Reddit comments about DO WHAT THOU WILT P. Here are the top ones, ranked by their Reddit score.
In addition to the great recommendations from everyone else this is a terrific biography that's pretty objective and and this is an excellent book by Crowley himself in which he lays out the whole concept of his magical philosophy. It's good to start with either an abridged copy of Book 4 if you prefer print books or you can easily find a free digital copy of the full volume online since all his works are in the public domain.
Read the quote again. They take from Crowley's writings which one major writing is the book of the law. This is where Crowley states "Do what thy wilt shall be the whole of the law". Satanists have even made books on Crowley superimposing their goats head pentagram on it - http://www.amazon.com/Do-What-Thou-Wilt-Aleister/dp/0312288972
Very few Christians follow the law of the Old Testament. I'm talking about major sects of Christianity, not some obscure Hebrew roots or Messianic Jew types.
As I said, I'm not trying to be politically correct. Satanist groups are typically unstable and do not have a history of lasting centuries. They are generally very unstable people who generally can't organize any type of real church. They hardly participate in any charity.
I've done my homework on both Christians and Satanists, long before I engaged this debate with you.