Today I visited a church in which the speaker addressed the problem of evil. Near the end of the sermon, he appealed to this famous quote from The Lord of the Rings:
“I thought you were dead! But then I thought that I was dead myself! Is everything sad going to come untrue?”
The speaker then observed that yes, it is in fact so. According to Christianity, everything sad will indeed come untrue.
But this isn’t actually correct. Christianity doesn’t claim that everything sad will come untrue. Christianity is consistent with various eschatological theories (i.e. accounts of the final order of things) including three main accounts of the final state of the lost. And only one of those is consistent with the claim.
The main theory of the fate of the lost is that they will experience eternal conscious torment, a state of never-ending alienation from God where the lost suffer unimaginable torment in body and mind forever.
If anything is sad, that most surely is. And on this account, this enduring horror will never come untrue.
According to the second account, the lost will be resurrected to face a final punishment that will result in their ultimate destruction culminating in annihilation into non-existence. While this scenario is undoubtedly preferable to eternal conscious torment, it also ends in what is effectively the capital punishment of an indeterminate number of human creatures. That too is surely sad. And it shall never come untrue.
The final view, universalism, insists that as bad as things are now, and however bad they may become, nonetheless, eschatologically all things — including the lost — will finally be reconciled to God in Jesus Christ. Only at that time, and under this very specific scenario, will everything sad indeed come untrue.
So to sum up, Christianity does not promise that everything sad will come untrue, but universalistic Christianity does. That may constitute a reason to consider universalistic Christianity, but that reason must be weighed along with all the other cumulative arguments (biblical, theologial, practical, philosophical, etc.) for and against the view. Suffice it to say, until one has a settled opinion on the matter, one ought to refrain from making claims about Christian doctrine that are not borne out by the facts.