Moral scepticism is the philosophical position that will most frequently be defended on this blog.
As a moral sceptic should I believe that there is nothing wrong with murder, rape, dishonesty, cruelty, and mayhem ... and ...?
Well, actually no. I certainly don't believe any of those things, and nor should I. I believe there are very good reasons to prefer kindness to cruelty, loyalty to treachery, non-violent resolutions of conflict to violent ones. In fact, I probably share most (though perhaps not all) of the same core moral attitudes as you.
I can't speak for everyone who has ever claimed to be a moral sceptic, but all I mean by the expression is this. A great deal of ordinary commonsense thinking about morality, as well as a great deal of philosophical thinking about it, asserts, or simply assumes, something that is not true, as far as I can see. It asserts - or assumes - that morality is "objective" in a sense that transcends the desires, interests, values, and fears that human beings actually have.
By contrast, I see the moral norms that prevail in particular societies as arising historically from just those sorts of desires, interests, values and fears. Moral norms ("don't murder or lie"; "be kind") can very often be justified, but the justification will need to appeal to actual human desires, etc. Beyond a certain core, morality may be somewhat underdetermined, its detailed content a product of ongoing bargaining and compromise.
This way of thinking about morality may not make a lot of difference for many important purposes, but it does seem, to me at least, to entail some far-reaching changes to the way we think about morality in the abstract. It also affects how we should consider some of the practical moral decisions that arise socially. It can affect what substantive positions in moral philosophy are intellectually supportable. In particular, I think it implies that many of the more peripheral or unusual examples of whether such and such would be the "right" or "wrong" thing to do may not have clear or determinate answers. Again, some conventional moral wisdom may be without plausible justification.
All that said, most of our core commonsense morality can be justified quite easily. For example, it is not going to be terribly hard to justify having a rule that forbids killing people who fear dying, though there is a great deal more to be said about the detail of this - and I doubtless will say more in future blog posts.