The argument from morality is scary.

[CapnAwesome]

Are you really so convinced that it will be better if everyone just became atheist?

Sort of a lot crammed into that really long paragraph, so I'll just focus on the question at the end. Personally I don't have any concern with trying to convert or rather de-convert anyone. Maybe Christians are being honest that the bible or their belief in god is the only thing keeping them back from being raging psychopaths. In that case I'd much rather that they kept whatever belief they had before.

I also don't think de-converting automatically makes you commit less crime. I think that being an Atheist is correlated with other factors that are linked with lower crime. Higher IQs, middle-class backgrounds, etc. I think that is the likely explanation for the lower crime rate amongst Atheists.