So, my mother is an atheist. She knows I'm a theistic Satanist, but aside from discussing the general philosophies behind the LHP, we haven't really talked in depth because she pretty much doesn't believe in spirits or entities. I find this pretty amusing because she's had some really weird experiences around me.
*Total side note, but when I was a teen, I kept a monster under my bed. MUTB bed down and I think eat dust bunnies... we had wooden floors. My mum went into my room with the dust mop, and I specifically told her, please don't dust under my bed - the MUTB won't appreciate it. She did anyway, and the broom "got stuck" (by which we all mean that my MUTB grabbed it and wouldn't let it go again). She yelled down the stairs for me to come to help her, and I had to bend down and talk to the shadows under the bed, saying, "Please give back the broom. I promise she won't ever do this again. Mum, do you promise?" "Yes. I won't bother him again." The broom came loose and shot forward to land at her feet. I still remember the look on her face... she really didn't believe me until that moment. However, of course, she's "conveniently" forgotten that experience, because, in her mind, she can't be an atheist if invisible things are real.
So we don't talk about invisible things. Instead, we talk about philosophy and ethics and what personal responsibility means. She knows I work with demons but she's decided that actually means I'm just confronting my issues by externalizing them through ritual. *shrugs*
Anyway... my dad doesn't know, but I haven't seen him in five years, and I'm not likely to see him ever again, so... it doesn't matter whether he knows or not.
I'm out on facebook, so it's probable that if other relatives are actually paying attention, they know - but none of them have asked me about it or acknowledged it in any way at all.
My husband knows everything. He knows I work with demon companions and spirit companions, he knows I'm a theistic satanist and demonolatress. He knows I've been doing demonolatry Goetia, and he knows I'm working my way into the Qlippot. He's gone to work with Tease a few times when things were really bad - his work is sometimes pretty dangerous, and sometimes the danger comes from other people just flat out being careless and not doing their jobs, so Tease goes to work with him to kick people in the ass and get shit done... or get those people gone.
My son I don't think knows - but I haven't been hiding it from him so much as he's just got his own life and he's busy living it - and we really only talk when he's having the typical troubles of a young man today - our phone calls are basically me telling him, "This is what I lived through, and this is how I dealt with it, and this is the consequences, and this is what I learned." If he ever asked, I'd tell him.
I don't believe in keeping secrets from my loved ones, but mostly, they don't care what I believe, as long as I'm a good person, which they think I am.
Each family is different. Each relationship is different. Knowing the people in your life well enough to know what you can talk with them about, and what they'd prefer to not know, is important to how you come out about theistic Satanism and spirit work... or really, anything.
If your family is strictly religious, or if they prefer the don't-ask-don't-tell approach, or if they're openminded and willing to listen - well, only you can really know that. Use your past experiences with those people to determine how you choose to approach this.
Remember that not talking about something isn't the same thing as flat out lying. Remember that you are entitled to privacy, and if you need to keep this aspect of your life private to protect your relationships, and those relationships matter to you, then you keep it quiet.
If you want to be out, and there are people in your life who would not appreciate it... be out to the people who can, and let the people who can't think what they will. You can always come out - there's no time limit. If you need to wait until you're on your own, do that.
If you really want to come out, start laying the groundwork ahead of time. Start talking, not about the Demon Lords, not about companions, but about the philosophies that the LHP has formed around. Talk about the 11 laws that LaVey set out. Talk about the nature of personal responsibility. Talk about the way the LHP stresses consent.
The more you talk about the philosophies and where you stand ethically and morally, the more comfortable you make other people... so that if "I'm a theistic demonolater and satanist ever comes up, you've laid the groundwork to be able to say, "Well, yeah, everything we've talked about, that's Satanism."
Good luck, and trust what you know of the people in your life.
