I wouldn't recommend trying to convert anyone to Satanism, as it might prove to be detrimental.
What is a more logical approach, would be to subtly talk about her beliefs in a normal relaxed(casual) way, which doesn't either seem offensive, or intrusive.
kinda like going out for a coffee kind thing(although I hate that cliche method, and reference .)
Trying to convert anyone to anything is incredibly rude. While it is ideal to find a Spiritual Satanist for a wife, it's not realistic :/
Nevertheless, I'm just saying, in general, try to spend time with the other person, and their beliefs will come out either naturally, if you observe them closely, or you might be able to do the above. Just start a random late night talk, or whatever works in the relationship. It's really a give and take thing as well, so be prepared to have to fess up something.
I've personally chosen to remain single for multiple reasons, but more power to you if you can make it work.