Norsefire,
Nobody can explain to you why these things are considered, by and large, to be "wrong". In fact, there are varying opinions as to how severe the aforementioned practices are, and I'm sure many people have exceptions for them, too. People may consider murder to be "wrong", but there are always exceptions: self-defense; warfare; capital punishment; etc. Stealing is the same: is it "wrong" to steal if you have no other way to feed your family? The only reason these practices are universally considered "wrong" is because we have laws in place dictating so. Furthermore, those laws are based on a given society's standards of morality, which itself is based on religion. Essentially, unless you have religion telling you what is and isn't "wrong", there is no way of concluding which practices are permissible, and which practices are wrong. Left to themselves, people will do as they please, meaning some will engage in these practices because they won't think it's "wrong" (regardless of what the victim believes).
Kadark