It takes an awful lot to make a high school kid shooting another high school kid over a confrontation into the fault of the LGBTs. None of that transgender or homosexual-friendly textbook stuff was being taught in 1997 in Pearl, Mississippi when 16-year-old Luke Woodham shot and killed his former girlfriend, Christina Mafee, and another person at Pearl High School, and nobody would think to blame heterosexuals or heterosexual-friendly books for that, despite the fact that Woodham was clearly upset over the end of his heterosexual relationship with Mafee.
That was Madalyn Murray O'Hair, in the case Murray v. Curlett (1960), which was eventually consolidated with Arlington School District v. Schmepp (1963) and heard before the Supreme Court in 1963, which decided that mandatory public Bible reading by students in public schools was indeed unconstitutional. There is still nothing saying that students can't read the Bible privately at their public school, or even lead Bible readings or discussions at their public schools as part of voluntary school clubs. Please see the U.S. Department of Education's guidance on this
here, which states in part:
A public school and its officials may not prescribe prayers to be recited by students or by school authorities. Indeed, "it is a cornerstone principle of [the U.S. Supreme Court's] Establishment Clause jurisprudence that 'it is no part of the business of government to compose official prayers for any group of the American people to recite as a part of a religious program carried on by government.'" Nothing in the First Amendment, however, converts the public schools into religion-free zones, or requires students, teachers, or other school officials to leave their private religious expression behind at the schoolhouse door. The line between government-sponsored and privately initiated religious expression is vital to a proper understanding of what the Religion and Free Speech Clauses of the First Amendment prohibit and protect. Although a government may not promote or favor religion or coerce the consciences of students, schools also may not discriminate against private religious expression by students, teachers, or other employees.
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In short, prayer was not banned or taken out of public schools;
school-mandated prayer and Bible-reading was.
The rest of your reasons are naked political tribalism, so I don't think they're worth anyone's time to reply to, but on the oft-repeated "liberals took prayer out of public schools/banned the Bible in schools" charge, that's simply not true.
School-mandated prayer or Bible reading is not the sum of those activities.