Separation of church and state in the United States:

Jeffries and Ryan (2001) argue that the modern concept of separation of church and state dates from the mid-twentieth century rulings of the Supreme Court. The central point, they argue, was a constitutional ban against aid to religious schools, followed by a later ban on religious observance in public education. Jeffries and Ryan argue that these two propositions—that public aid should not go to religious schools and that public schools should not be religious—make up the separationist position of the modern Establishment Clause.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". What was the central point of the rulings of the Supreme Court's rulings?
constitutional ban against aid to religious schools