Help me refute the "suffering will be insignificant in heaven" theodicy

[Belacqua]

what Christianity actually teaches

Unfortunately, what Christianity actually teaches is a lot of different things, because there are a lot of different versions of Christianity. 

Different traditions may be incompatible to the point where they are all called "Christianity" only in Wittgenstein's sense of "family resemblance," and not through any essential continuity. 

That doesn't mean atheists have to consider every possible conception before rejecting the whole idea.

This is true. If you're not interested in the subject, there's no reason why you should have to waste another minute on it. 

If you want to make a video rebutting some aspect of Christian theology, however, it makes sense to know what Christians say. And there may not be a single argument against everything they say, because it varies.