Many people think that the moral principles of that kind are blinders, which don't allow you to see some exciting secrets. In fact, they are eyes. There is a whole section of reality you will not see without them.
Moral laws are like other laws of science. It does not mean that you cannot do evil, but if you do evil, the results will be evil. It has nothing to do with the iron law of karma or divine justice. You can do very well out of it. But the final results will be evil - not necessarily right away.
And if not - in that case, the law was badly formulated. There can be mistakes in morality, like in any other science. In fact, there are much easier - because that science is much more difficult.
This because of the rule of complexity - if a system has many elements interacting in a nonlinear way, you cannot deduce the behaviour of the system, even though you know the behaviour of the elements and it is completely deterministic. (And, obviously, in reality it isn't, because of quantum mechanics. The possibilities are deterministic, but which one of them will happen - it is not.)
Because morality describes the most complex system available for us, it is obviously the most difficult science possible - even without taking any spiritual elements into consideration (and, obviously, you have to).
There is a very interesting thing with complex system - there can emerge new properties in them, which cannot be deduced from their elements, and cannot be named using terms describing them.
See Standish, On Complexity and Emergence
Eg - living and dead. There is no physical or chemical difference between live and dead cat. There is no elan vital in one which you can discover as a new chemical compound or element. You cannot define it, that is (not to begin that discussion again) you cannot reduce it to chemical or physical terms. (You can define it good enough for any sensible man - but you need a sensible man first. You cannot define it for an automaton).
It is counterintuitive, but increasing complexity is in many respects undistinguishable from randomness. In fact, when you use eg Kolmogorov measure of complexity (the length of algorithm generating a given pattern), the random pattern is the most complex.
The difference is that the random pattern has no meaning. You don't need to copy it exactly. Any other similar random pattern will do as good. But really complex pattern makes sense - but only for those who understand it. For all of the other it could be as well random.
In that way, when you understand a new idea, a new word, you begin to see a new part of the world - and the other way round.
Here is an old speculation (not my own, it was a hobbyhorse of a mad Polish SF writer Adam Wiśniewski-Snerg). There are four known levels of beings - stones, plants, animals and men. No being can understand anything from a higher level - eg for dogs we are only bigger dogs. So should we see some higher being, of eg 5 level, we would see only a strange man - at best.