To love mankind for the sake of God - that has been the most noble and far-fetched feeling yet achieved by human beings. The idea that without some sanctifying ulterior motive, a love of mankind is just one more brutish stupidity, that the predisposition of such love must first find its weight, it’s refinement, it’s grain of salt in another even higher predisposition. (A. 60)
This aphorism from Neitzsche's Beyond Good and Evil posits an interesting though experiment.
If God didn’t exist, does that mean that these actions are, as Nietzsche states, just brutish stupidity? Isn’t acting morally something that doesn’t require God’s decree to do? If so, then that means that acting for the sake of God is not necessarily the most moral act. In fact, we use God as an excuse for our actions, regardless of their morality.
This idea of 'God' creates a cultural and religious representation of morality. We then operate on a constructed belief of what socially should be right and wrong, and not truly what is right and wrong. This is why different cultures and regions have their own understanding of morals.
This suggests that our first principles of right and wrong, are in fact not first principles. They're derived. If morality is constructed, then what is the true first principle we must reach to paint our way to act and live? And - does it even matter what the first principle is?
If the idea of morality is constructed, that means that we all, consciously or subconsciously, create our own version of what's moral or immoral. It's just that most of the time, this construction is heavily influenced by an idea of a universal (more like regional) God.
We must all find our own inner gods, and act for them, rather than act for a universal God. Those actions and beliefs are what will dicate our own morality and our ability to accept our actions as true to one's self.