What if there was no religion? What if everyone was an atheist? How would the world look like? Would it be better or worse for planet Earth? For humanity?
Allow me to frame this question in two ways.
First, suppose that society and homo sapiens developed without religion. How would've that looked like? Is it possible for a being to evolve intelligently and remain non superstitious? Where would we be now?
Second, suppose that the next generation decides that religion isn't for them and atheism becomes the majority "religion". How would the near future look? Where would society go if humanity began discarding religion on mass from this point on?
The problem with this question is that there is no meaningful way to distinguish "religion" from other ideologies.
Humans require either religion or some functionally equivalent ideology.
While people often think of religion as being divisive, it is probably the biggest unifying force ion human history. The idea it is divisive assumes we are naturally united unless something divides us, but this gets the process backwards. We started off as atomised small groups and required things like religion to create artificial bonds of kinship that allowed us to form cohesive groups larger than can be maintained by direct personal relationships (which is why our close relatives like chimps live in small groups).
So to form societies we needed religion or a religion equivalent. If we didn't have this we would still live in smallish communities, and if we did invent this it would have the same effects as (man made) religions do.
If now everyone became irreligious, we would see many new ideologies emerging as people don't simply renounce religion, they replace it with something else. The parts of the world that are most religious now would likely be the major source of these new belief systems as many irreligious world views are heavily dependent on the Western cultural tradition.
Any idea that can be framed in religious terms can easily be framed in "secular" terms too. Many of the people attracted to rigid, dogmatic religions would find new rigid, dogmatic ideologies and we can absolutely guarantee, is they wouldn't all (or even mostly) become moderate Secular Humanists.
Basically there is no way of knowing what would happen, so there is no reason to assume that it would make anything better and it could very easily make things worse.
