And where is that line? How far out should it be? You want the government to FORCE a private religious institution to not be allowed to set their own acceptance standards. Thats pretty far out for me.
And this goes back to the conflict of equality and freedom to practice religion.
Many want to draw the line at "What you cannot change about yourself." This would include color, race, sex (well, you can change that now, to some degree), and others. Many people believe that sexual orientation also cannot be changed.
In your example, one can practice and generally improve their musical ability, but one cannot easily practice and improve their caucasian-ness. (Although Michale Jackson appears to have attempted the feat)
But that line is still drawn further back when it comes to religion, specifically due to the first amendment, which allows people to freely exercise their religion, and also allows citizens to peaceably assemble.
By definition, religions and clubs are allowed to exclude people based on in-born traits.
Still - what if the school accepted gov't funding per student that would normally go to a public school, and thus comes from people's taxes? The money would be spent either way, yet it sounds like that might cross a line for some...