philosophy discussion

Many people think that morality is relative to culture. What is right or wrong is determined entirely by what a group or culture believes to be right or wrong.

Suppose there is a society, call them the “Pazi Culture”. The Pazi believe that violence against other cultures is good, and that they are the supreme culture. So, they go on a campaign of not only disparaging other cultures, but also violently assaulting and even raping and killing members of other cultures in order to ‘purge’ the world of inferior races and cultures.

If morality is relative to cultures and there is no absolute moral principle, is there any way that we can truthfully say that what the members of the Pazi culture are doing is absolutely wrong? Explain your answer.