I think God is necessary for absolute morality. Godless society or system will also be agreed upon certain morals, values or ethnics to run the society but these morals would not be absolute and may also evolve over time. For example what was considered immoral in past could be interpreted as moral in present for example gay marriage
'Morality', 'Humanity', 'Honesty', and such 'Evil' are merely just social constructs created by our societies. There is no rational reason to believe in them.