I think it's fair to say "religion X causes honor killings" if and only if X's teachings encourage them (by explicitly saying there's no spiritual punishment for them, for example). It's also fair to say that "religion X doesn't cause honor killings" if there's no correlation between religion X and honor killings. I agree that correlation on its own is never enough.

So: do the teachings of those with a mantle of religion-X authority, on average, encourage or discourage honor killings? This is not a question we should avoid asking just because we want to be nice.

I don't see any evidence that Sam Harris has got this wrong.

Good point about being nice vs. reaching a permanent accommodation.