here are things that have always been wrong and will always be wrong and at no time in the past or future could ever be right. Slavery is one example, murder another.

One would imagine so, but this is sadly not the case. Slavery, as you probably know well, was moral and legal for centuries. As a matter of fact, here in America, the Bible was used as a way to justify it's morality. (Bible has examples of slavery in the old testament)

Along the same lines, but much longer ago. Murder was completely Ok, as long as those being killed deserved it for not believing in the correct God. Now... today, with very little exceptions of course, humanity agrees Slavery is wrong and Murder is despicable... Even so, they are not completely abolished either.