If nowhere else, in the relation between Church and State, “good fences make good neighbors.”

Felix Frankfurter (1882–1965) American jurist, teacher; US Supreme Court Justice (1939–62)

McCollum v. Board of Education, 333 U.S. 232 (1948) [concurring]
    (Source)

Ruling that public schools could not let religious groups use their property for religious education to children.

The quoted reference is to a poem by Robert Frost.