For example, I have a Christian friend, he is starting to doubt Christianity
It really depends on what you mean by communication. A non-Satanist doing a Standard Ritual is one type of communication. A non-Satanist addressing Satan in prayer is another type of communication. There are really many cases, although in some cases it would be better to wait for the Dedication, PERSONALLY I think that in others we can address our original Gods as such.
A while ago, a friend of mine and I were doing the Ouija board with Azazel for a girl who wasn't a Satanist. The girl started asking questions to learn more about this Satanism thing (I don't remember what questions), and I was dubious because I said: "Azazel would definitely never want to answer to someone who isn't even a Satanist", then, turning to the Ouija board, I asked: "right?".
The plate went to No, denying my black/white binary beliefs. The Gods are available to help honest and sincere people. When they attack those outside of Satanism, they don't do it because they are "not dedicated", they simply make themselves respected by the blasphemers who try to abuse them.
But I don't think that those with an honest heart should worry about going to the Gods just because they haven't done the Dedication yet. I discovered JoS when I prayed to Satan and mentally asked him: "I would like to join Satanism, and get to know you better, but every time I try to learn about Satanism I only find macabre and senseless stuff, please, manifest yourself to me". There it struck me in the head: "itajos" (the old name of the Italian site). I swear.
Of course there are many ways to go to the Gods. But even mentally praying to Satan asking for a little guidance IS a truly SACRED way to talk to him, it's not all evocation or no evocation.
