Rockhead wrote:Why is all of us repeating a mantra as a unit SO important to the function of us all?

Because, like it or not, ritual is essential to human society. Now you and your fellow "Progressives" will likely argue that ritual has no place in your mind set or world.
Baloney!
Every time the "Black National Anthem" is sung : Ritual.
Every time a Democratic nominee's convention committee worries about the nature and color of food to be served: Ritual
Every time a Democrat invokes the memory of John or Bobby Kennedy: Ritual.
What is wrong with requiring our children to engage in a ritual that strengthens their personal affinity with their national community?
Oh, I know...there's that nasty word "require." We should never require anyone, let alone children to do anything!
Well, we require children (and adults) not to urinate wherever they please.
We require children (and adults) not to take whatever item appeals to them, irrespective of who may own it.
We require children (and adults) not to prance around public places naked.
We attempt to require children not bully other children or call them insulting names.
We require children to respect adults --- oops, not so much.
But you're right, it is a silly mantra and no one should be required to do anything.
Because, as anyone who has children will tell you, there is no need for adult intervention in the personal and social development of kids. Leave them to their own devices, requiring nothing, and they will perforce turn out to be find upstanding members of society.