There is nothing more dangerous than families with money, brains, and weak or no beliefs. Harvard-Westlake, La Jolla Country Day, and Francis Parker are private schools that have no religious element. I would never allow my children to attend them.
We send our kids to Evans/Bishops because they are private and religious. We believe that kids need both to learn and to, more importantly, develop proper character.
Private schools without religion merely ensure that your kids get higher quality drugs than the kids at public schools get.