The question of whether a state has the right to establish a religion is an issue for the state and it's Constitution and laws, not the Federal Court, because neither Congress nor the Court has authority to regulate religion..
Established state religions existed in the United States for many years after passage of the Constitution and first several amendments, Massachusetts ending the Puritan state religion in 1833.
"No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States"
The 14th Amendment extended citizens First Amendment rights to the states but does not prohibit states from establishing a religion. Both states and citizens have a Constitutional right to "the free exercise" of religon, but the Fourteenth Amendment puts citizens rights above the states.
Therefore the Constitution continues to protect the rights of citizens to establish a religion, but their religion must respect and not infringe on the beliefs of the minority.
Early Court interpretation of Fourteenth Amendment limited the "privileges or immunities" clause to the abolishenment of slavery, but it was later expanded to other issues applicable to the rights of citizens. The 14th Amendment should protect, not ban, the practicing of religion in schools and other places under the authority of government, because the rights of the majority do not cease at the door of a class room any more than do the rights of the minority.
The First Amendment Establishment Clause cannot be applied directly to the Fourteenth Amendment. Citizens "privileges or immunities" allow them to be free of laws infringing on their rights, but a law establishing a religion does not infringe on those rights unless or until it affects the citizens rights. Similarly, citizens in the majority are awarded the same privileges or immunities by the Fourteenth Amendment including the right to religious freedom in or out of a public building, if they are in compliance with other laws and policies.
In Bill of Rights, writer Kerby Anderson outlines the first ten amendments and intention the "religion and state" clause..
"Originally the religion clause of the First Amendment was intended to prevent the federal government from establishing a national church. Some New England states maintained established state-churches until the 1830s.
In the last century, the Supreme Court has extended the First Amendment to any religious activity by any governmental body. The establishment clause originally prohibited the establishment of a national church by Congress, but now has been broadened to prohibit anything that appears like a government endorsement of religious practice. The free exercise clause supposedly prohibits government from placing any burden on religious practice." (Reprinted with permission)
No reasonable Constitutional basis, nor legal justification exists for the more recent judicial change from states' to federal authority, but may be, rather, simple judicial activism. A long string of federal court decisions can legally clarify, but not alter the meaning of the Constitution. A court attuned to the rights of states will roll back the federal intrusion in states' rights.
The States' Liberty Party advocates states' rights, not necessarily the establishment of states' religions.