In Christianity, there is the idea of the Rapture, in which - if I understand correctly - the good are taken to the afterlife, while everyone else remains on Earth.
Take an alternate Earth. Sometime in the near future, something like the Rapture occurs in a manner agreeing with the beliefs of religion X.1 However, the deity of religion X decrees - just before leaving - that this will happen a second time (and perhaps more beyond that) when those still on Earth will have a second chance.
This has some interesting implications. It gives some pretty strong proof that religion X is correct. It also means that those remaining on Earth have some motivation to do everything possible to do enough good to be accepted to the afterlife the next time.
The beliefs of the mainstream sect of religion X state that violence is unacceptable for most reasons (the exceptions being self-defense and the punishment of those who commit violent crimes). One would assume that people would, therefore, cease fighting, as violence could prevent them from being rewarded the next time this Rapture-like event happens. There might be exceptions, though.
Would wars still happen after a Rapture-like event? If so, why?
Edits from comments:
- There is proof that those who were taken were brought to the afterlife
- It is implied that those who were taken will go to "heaven", while those who remain have a good chance of going to "hell"
- There is no "deathbed-confession-of-sins/conversion" that would save somebody.
1 All the religions in this world are different from the religions on our world, so religion X is not meant to correspond with any particular religion.