If religion were gone there'd probably be more people on earth due to the lack of all the religious killings
I think that's a joke I heard somewhere.
Taking the statement seriously, I'm not sure about that. There would be no one vehemently going against contraception and artificial family planning. Lots of cultures and countries would not have spread/ expanded without religion. Also, like it or not, many people survive from religious charity and a good number of donations are given as payment for a ticket to heaven.
But, there would be less restraint on sex. There's also the portion of the population who would be free from celibacy. It's tough to estimate the effect. Well, war and terrorism will happen regardless of religion. Religion is sometimes just an excuse or a tool.
Meh, people would be more open about their reason to kill. Like for land, wealth and whores.
They use religious reasons for the same goal, but the excuse sounds better morally and more acceptable by populace.
though by vocal sounds one should decide on their own:
For the Emperor !
For God Almighty !
FOR PLUNDER AND BOOTY!
FOR THE HORDE !
FOR AIUR !
For Justice !
Funny though I never heard:
"For Freedom and Justice!"
"For Freedom ! For Justice!"
as they are separate reasons, cuz how do you justify killings as just ?
Morally you can't, hence as the society grew more moral/immoral the "For God Almighty!" took over the rest. Kill heathens that won't convert is morally accepted, even today. But killing for booty, sex, wealth is just plain banditry and is not being morally accepted. Even though they end up the same way in most cases, alas with more booty and raping than wealth cuz most of the wealth is in banks now.
So religion was really established as an excuse to rob people of their belongings and justify murder. If you trace back the Crusades you'll probably stumble on chronicles about how many people were literally slaughtered in blood-lust without even attempted conversion, women AND children raped and indoctrinated into slavery, and the amount of pillaging done.
The only order that actually broke out of plundering and murdering in teh name of teh church was teh order that reformed istelf into the Templars. Mind you they are not pure and innocent of all their sins during teh crusades, but they woke up from the mind control and decided to blackmail the church if they are not released from direct control of the Vatican.
They kept all teh wealth they amassed, but were eventually hunted down on friday 13th.
So if religion would be gone, the only thing that would change is ... reasons for killing
If GREED was gone.
We would be overpopulated I guess.