If one takes full account of the persecution of heretics, the frequency and savagery of the religious wars which Christianity had endangered, the harm caused, especially to children, by the pernicious doctrine of original sin, a case could be made for saying that the world would have been better off without Christianity.
A prevalent fallacy is the assumption that a proof of an afterlife would also be a proof of the existence of a deity. This is far from being the case. If, as I hold, there is no good reason to believe that a god either created or presides over this world, there is equally no good reason to believe that a god created or presides over the next world, on the unlikely supposition that such a thing exists.
If the assertion that there is a god is nonsensical, then the atheist's assertion that there is no god is equally nonsensical, since it is only a significant proposition that can be significantly contradicted.