Group selection doesn't work.
Well what exactly is "group selection"? If a group of people has a particular belief; and as a result of that belief, the group increases dramatically in numbers, would it qualify as "group selection"?
Conversely, if a group of people has a particular belief; and as a result of that belief, the group decreases dramatically in numbers, would it qualify as "group selection"?
It would not qualify. The ultra-Orthodox Jews example you give is of a set of individuals each pursuing their own fitness, and the set does well because each individual in the set does well. Group selection specifically refers to practices which make the group better off at individual cost. For example, if you had more daughters than sons, your group could grow faster- but any person in the group who defects and has more sons than daughters will reap massive benefits from doing so.
The moral of the story is, some people are oversensitive to "group" in the same sentence as "reproductive fitness." Try to avoid it.
Here's the new thread for posting quotes, with the usual rules: