To expound on what others have said, I think people are too distracted by the belief in a higher entity to see religion for what it mostly is. I see it as being highly cultural, and because of this, presume culture would be the prime candidate to replace religions's ups and downs had the latter not existed.
As a kid/teen, if I had brought home some cooked cat or dog from the store, I would have at the very least gotten grounded all the way to heaven . As an adult, if I slept with a pillow that had a provocative anime girl on it, I'd be mocked to hell and back.
We humans don't have much aptitude for absolute indifference toward behaviors, and behavior is all we are. There's many behaviors that I'm sure everyone deems disgusting or weird. If you wouldn't want your kids to learn it, or your family's participation, then it's safe to say you most likely hold some kind of negative view toward it. There is little conflict because one culture isn't trying to force its behaviors on another. Another key detail keeping culture a step away from religion.
Marriage (this includes whether *** takes place before marriage, the justifications for divorce, how old you're allowed to be before you marry etc,), celebrations/holidays, funerals (how the dead is buried), appearance (clothing/grooming), sports, etc. can all be dictated by culture alone. Without any belief in a higher entity or afterlife. As in my own personal case, prohibition of certain food was GREATLY encouraged. As a child, you adopt these beliefs and peconceptions without ever feeling the need to challenge them. It's all just so normal to you. Religion governs a lot of the above mentioned, if not all. Yet an atheist or agnostic can be just as conditioned in all the same categories that religion moderates.
Look at all the attitudes toward "black culture". You hear the complaints all the time, "Just because I'm black doesn't mean I listen to rap, or play and watch basketball." This perception just goes to show how residing in the same country can still produce very large differences among communities. You have people arguing, using whatever statitics, that blacks are more likely to drop out of school because of their mindset or "culture". Certainly such views have nothing to do with religion, yet people are discerning behaviors between different groups of people and fighting over it.
Perhaps the most evident case, is the one where for many years, millions of whites, because of how they were raised, mistreated and even killed many blacks...
You have people who apparently ignorantly bash the entire Indian culture as a result of hearing about just a few events.
Look at how much support Donald Trump is getting after making drastic generalizations (especially about Mexians).
If you believe religion is man made, then it comes down to the following...
Society: Let's think of ways to keep the people and thus the community under control.
Religion: Let's think of ways to keep the people and thus the community under control.
One thing I was able to get a clearer picture of after reading through all those quaran quotes members be posting here on NB, is that both religion and society in general make their rules to either remedy a current problem (or foreseeable one) or gain more control. Granted, society can be more innocent in its influence, all it takes is one celebrity to start some kind of trend, after all.
Whichever it is, the decision always impact the way people behave and interact with one another in their day to day relations.
So yeah, I think we're actually looking at ourselves when we look at religion. The supernatural aspect is just dirt on the mirror.
PS. I'm agnostic