I'm just gonna make this short and to the point. I understand that Satanists are to indulge in the teachings and life itself, but is sleeping with a married man correct ot unjust? Please someone give me insite..........

I'd say it's all in context of the situation. One makes their own morality, and I'm not sure what your personnal situation is (if this in fact deals with you).

Let's say the husband is Mr X
the wife is Ms. Y
And the, um, third party is Ms. Z

I would say it is Mr X's duty to keep his wife Ms Y informed of what he is doing. It's not Ms. Z's concern whether he does this or not, unless Ms. Z and Ms. Y happen to be friends or something. In which case I would say Ms. Z should be careful about getting into a sticky situation.
Who knows? The wife could be very well aware of her husband's, er, side projects, and even approve of them. And swinger's clubs exist for a reason.
I can say this with a little experience because I have been a third party in a very dramatic triangle that I should have stayed the hell away from. I fell in love with someone who was already "taken." I have never agreed with the possessive aspects of relationships, but that's just me. I think as an individual you have to take all things/people into consideration to come to your own conclusions about what is "right" or "wrong" here.

That takes a lot of clarification.

First, I'd just assume if this is an ethical question for a Satanist, that means he's married and doing whatever without his wife's knowledge/consent.

Second, it might depend on whether he's separated. My mate was technically married by law when we met...but hadn't lived with her "spouse" for about a year, and was in the process of a divorce.

The real question is, how do you feel about it? Is his wife a good wife? Is what he's doing harmful to anyone? Could it be harmful if he's found out? Would you mind telling her that you are screwing her husband?

Also keep in mind that Hell hath no fury like a woman scorned...willing to take that chance?

Hmmmm,,,,thats a tough one..to quote the Satanic Bible..."as long as it doesn't hurt anyone" from 'Satanic Sex'...that could be anything...imo,if the parties who may be hurt by "the affair" do not matter one way or another to you...then go at it...I suppose the answer is...if the grief you may recieve by "getting caught" if that happens is too much,then its not worth the risk..