Where does the assumption come from that there must be absolute, cosmically-dictated morality? There's no empirical justification for such an assumption that isn't explained by the inborn inclinations of social animals.
If it ever becomes evident that there is such a thing as morality with a capital M, then we can start figuring out which acts are truly right and wrong. Until then we're forced to settle for our best attempts at a general consensus.
As much as we might want an absolute morality, it doesn't seem to me to be the universe's job to hand us one. Our desire doesn't make it so.