I do believe that humans just naturally decide what is moral and what isn't in this day and age. There are some religions that take things so literally and it gets way out of hand. The Bible is just, yeah, full of metaphors. If we were all a bunch of kids at the same time, with no adults, we'd more or less kill ourselves.
Religion was the thing to believe in then, so it obviously comes into play with morals. Now it is certainly possible for atheists to have morals, and anyone else for that matter. Just then, 99.9999% of people were religious, so I guess it bags the credit. People were easily led. If everyone was atheist, then there'd be questions for everything and too many people would panic. So yeah, setting up morals had to be associated with religion for people to follow it.
If you call someone who isn't of your religion immoral now because of that then it's just flat out ignorance.
People still manage to have different morals now. Somehow almost everyone has lost touch of what they were taught, I think that this is mainly due to parenting though. I just die a little inside when people litter, IT'S MORALLY WRONG TO ME. So yes, I think that in a century everyone will pretty much do this, same with swearing. No matter how disgusting it is, it's part of language change.
What is right is just what's logical for everyone to be happy. That's... good... isn't it?