Good stuff there. Thanks for the continuing nice and well thought out replies. You sound a lot like how my father describes many of his friends.
On the religion in public places, I often think of the line, "When you are accustomed to privilege, equality feels like oppression." Its a bit trite and certainly not a one size fits all pearl of wisdom, but I do find some truth in it.
As for the shootings, there is definitely something different, but I don't know if we could ever pin it down because so many things are different from the way-back. Your link mentions mental health, and we have definitely changed the way we handle that (some good, some perhaps less so). Our world has also gotten smaller. More people in less space. Also, much harder to disappear now if things aren't working out. Certainly race relations are different now. Along those lines and for a positive societal change, compare lynching statistics to mass shooting statistics. I'm not claiming at all that they are related or anything, but in the year of the first mass shooting (germany-1913) there were 52 lynchings in the US. Society has changed in hundreds of ways over the last century and there certainly aren't any easy answers.