What was the key ruling in Engel v. Vitale regarding school prayer?

The key ruling in Engel v. Vitale centers on the constitutional principle of the separation of church and state as it pertains to public education. The Supreme Court determined that the New York State Board of Regents' voluntary prayer program, which composed a non-denominational prayer to be recited by students at the start of each school day, amounted to government endorsement of religion. This violated the Establishment Clause of the First Amendment.

The Court emphasized that even if the prayer was intended to be voluntary and non-denominational, the act of a governmental body composing and promoting a prayer for students compromised the neutrality required in matters of religion and education. This ruling set a precedent that any state-sponsored prayer, even if deemed voluntary, could not coexist within the public school system, reinforcing the principle that the government should remain neutral regarding religious practices.