What are the difficulties in using the wall of separation principle?

Answer 1

The first problem is that a wall of separation would violate the establishment clause itself by establishing secularism/Atheism as the National Religion. Since the purpose of the establishment clause is to prevent Congress and thus all branches the Federal government from establishing a National Religion, a wall of separation between church and state violates the establishment clause.

The second problem is a wall of separation could only be imposed by denying religious

citizens the free exercise of their religion so it runs contrary to the free exercise clause as well.

The third problem is that the Supreme Court itself began using a religious test to prevent aid from going to Catholic schools while allowing it to go to protestant schools. The court used the test that when the majority of schools are of a particular denomination, it appears to be an establishment of religion. Of course, the Justices fooled no one. The particular religion denied aid was always the Catholic church and in some of the earliest cases they even deliberately mentioned the Catholic church.

Also, the Court began changing the religious test to exclude all religious speech which violated the prohibition of a religious test and violated the free speech rights of religious citizens.