Sounds like a reasonable argument. The loss of community, I.e. the development of de-personalised housing such as tower blocks etc. seems to identify with the decline in social cohesion and criminality.

I’d like to do a study on that but don’t have the time at the moment.

You are right that there is a lack of community but large spaces will not fix it.

Could be but that is only one possibility of many.

Yes.

This guy's accent was so distracting I had to turn the sound off and just read the subtitles, but I think he's speaking to the same issue.

[ted.com]

It been said that, "We are creatures of habit." As such, we will bond to any group that is perceived as the norm, whether beneficial or not. Such is community.
However, community can be found in any alliance with like-minded people so I don't think that a lack of religion is a detriment to this social behaviour.