Both the right and the left are against this, despite the SCOTUS ruling that this was OK. In fact, this is probably the reason the ACLU hasn't filed suit to stop it.
Didn't the Supreme Court nix that kind of thing? No, it didn't, although that's a common misconception. The court ruled against imposing prayer on students in the public schools, not studying religion. To quote its decision:
"Nothing we have said here indicates that such study of the Bible or religion, when presented objectively as part of a secular program of education, may not be effected consistently with the First Amendment." — Abington v. Schempp, 1963.But how teach the Bible as just another part of secular culture?