I agree, but I think to say that there has to be some sort of transcendent morality is wrong. While there may be one, how do we know? How are we to determine how it manifests itself? Is it strictly singular in its manifestation (I.e. throughout time and place, it is no different) or is this single transcendent morality interpreted differently through different cultural lenses? C.S. Lewis gives good evidence for the latter in his Appendix in The Abolition of Man. Peter Berger also discusses this at length, (and in far greater depth) in The Sacred Canopy. Both are worth checking out if you’re interested.