The argument is not based on a Constitutional imperative. Religions are numerous, contradictory, diverse and largely false. They are also ostensibly concerned with the supernatural. This implies two things; believers can make all manner of outrageous claims to special instructions from God which men outside of the faith are not privy to; and, more importantly, they can justify the extermination or conversion of nonbelievers. While it is presently true that most Christian religions in the U.S. are relatively benign it is the intolerant fundamentalist faiths that will aggressively dominate the secular institutions at the grass roots level.
Once this door is opened it is only a matter of time before the group with the most extreme and aggressive followers is in charge and anyone who doesn't toe the line will find themselves in a hell of these zealots' making. It is this possibility, however remote, that must be minimized by the simple expedient of keeping any form of religion from being sanctioned by an attachment to government institutions.
"separation between church and state does not exist in the Constitution."The interpretation of the 1st Amendment can differ quite a bit, from "only no state-established church" to "no state involvement in religion." To get insight into what is meant by that amendment, it helps to read the writings of those who wrote or influenced it.
The phrase "wall of separation" comes from Jefferson in a letter to a baptist congregation worried about being persecuted by the then state-established religion. Below, he is agreeing with the letter from the church that government should absolutely not be involved in religion in any way:
"Believing with you that religion is a matter which lies solely between man and his God, that he owes account to none other for his faith or his worship, that the legislative powers of government reach actions only, and not opinions, I contemplate with sovereign reverence that act of the whole American people which declared that their legislature should "make no law respecting an establishment of religion, or prohibiting the free exercise thereof," thus building a wall of separation between church and State. Adhering to this expression of the supreme will of the nation in behalf of the rights of conscience, I shall see with sincere satisfaction the progress of those sentiments which tend to restore to man all his natural rights, convinced he has no natural right in opposition to his social duties."
"It was created by case law by the United States Supreme Court in 1964."All the Supreme Court did in 1964 was to not allow captive or forced prayer in a public institution. It said absolutely nothing about voluntary, student-led prayer. Any teacher or administrator stopping students from praying themselves (while not being any more disruptive than other allowable actions) is violating those students' rights and should be disciplined. This is NOT acceptable to anyone valuing our religious freedom. On the other hand, any person forcing students to be in a prayer in school ("Okay class, now we're going to pray...") is also violating those students' rights.
"One could argue the Supreme Court violated the Constitution."No, one couldn't if they knew anything about the Court.