How do human groups glorifying immorality imply that there is no universal moral code? If the universal moral code exists outside of those groups, then it can be applied to their actions, and we can call them wrong for the thing they glorify.
Your very sentence implies a universal moral code. You are calling murder, slavery, and genocide wrong. By which standard do you know them to be wrong? Such a standard must necessarily exist outside of the groups that glorifies the things you correctly call abominations.
Your very sentence implies a universal moral code. You are calling murder, slavery, and genocide wrong. By which standard do you know them to be wrong? Such a standard must necessarily exist outside of the groups that glorifies the things you correctly call abominations.
Edit: typos