My daughter and her friends were saying they were Satanists to piss off the "normal" kids. So I had her look up TST's 7 fundamental tenets. Now she really is one.
For those unfamiliar, The Satanic Temple is an atheistic organization. Here are its tenets. I often ask people what they disagree with and get very little in the way of meaningful response.
THERE ARE SEVEN FUNDAMENTAL TENETS
I
One should strive to act with compassion and empathy toward all creatures in accordance with reason.
II
The struggle for justice is an ongoing and necessary pursuit that should prevail over laws and institutions.
III
One’s body is inviolable, subject to one’s own will alone.
IV
The freedoms of others should be respected, including the freedom to offend. To willfully and unjustly encroach upon the freedoms of another is to forgo one's own.
V
Beliefs should conform to one's best scientific understanding of the world. One should take care never to distort scientific facts to fit one's beliefs.
VI
People are fallible. If one makes a mistake, one should do one's best to rectify it and resolve any harm that might have been caused.
VII
Every tenet is a guiding principle designed to inspire nobility in action and thought. The spirit of compassion, wisdom, and justice should always prevail over the written or spoken word.
No, nor do we believe in the existence of Satan or the supernatural. The Satanic Temple believes that religion can, and should, be divorced from superstition. As such, we do not promote a belief in a personal Satan. To embrace the name Satan is to embrace rational inquiry removed from supernaturalism and archaic tradition-based superstitions. Satanists should actively work to hone critical thinking and exercise reasonable agnosticism in all things. Our beliefs must be malleable to the best current scientific understandings of the material world — never the reverse.
As far as membership goes, yes kids are allowed. You can buy a membership card and certificate on their website, or you can just go and participate in one of their public events as long as the event doesn't mention any age requirements. My local chapter definitely does family friendly events.
They organize events on Facebook groups in my area typically. Just search for TST and your state name and you should be able to find a local chapter that does some sort of events.