OK, let's look at this from another angle here.
Public versus private. Public schools have to teach a set curriculum. One that is a "one size fits all" curriculum. Private schools, on the other hand, only have to have their students meet certain requirements (standardized testing), but are otherwise free to teach whatever they want - religion classes included.
Which produces better students across the country - public or private schools?
(Yes, I realize there are a lot of circumstances that could affect that outcome. But, it would disingenuous to say that allowing a school to cater to its students' needs doesn't increase student performance.)