There've been ongoing debates among intellectuals about morality and whether or not humans could be moral and secular. In other words, can people be moral without religion and/or God. The God-fearing insist any attempt at morality without God will always lead to a slippery slope of failed ethics (Morality comes from God!). The moral secularists insist it's always been people that decide what's moral, and that it ebbs/flows with culture; irrespective of God or religious institutions (or something to that effect). Humanism, or Secular Humanism has some overlaps with moral secularists.
What it boils down to is the God-fearing camp insists humanists are pompous and devoid of the rational belief in the source of all good. Humanists insist that religion, mostly, is the chief hindrance to the human race's progress as a species.
I'm pretty sure 'cannibal' lies way outside of these doctrines of though as it pertains to what's right/wrong to put on your dinner plate, but as another anon said: