In short, you can't walk in my shoes, nor I in yours, because the experience would kill us both.
You can't tell me how to be a man, because you don't know how to be a man, from my perspective, nor do I know how to be a man from yours.
That is the base fact.
Religion, however, gives us both some sort of equal footing to work with, hence build a neighbor, and then a neighborhood, and then a street, and then a village...and through it all we keep meeting on a regular basis, to affirm our beliefs, and to test our mettle on each other to make certain we are ALL complying in a basic standard that the "society" can function on.
Morally, legally, civilly.