(RNS) — The Supreme Court heard arguments on Wednesday (April 30) in St. Isidore v. Drummond, a case in which an online Catholic school in Oklahoma is claiming the right to be fully funded by the state as a charter school. The parochial school is challenging the Oklahoma Supreme Court’s ruling that public funds may not support a religious school. 

After a series of cases in which the court has been laying the groundwork that could force tax dollars to support religious schools, the conservative justices appeared more than ready to abandon separation of church and state to allow such schools to get full taxpayer support so long as there is a charter school system that permits anyone else in. 

If St. Isidore prevails, taxpayers will potentially have to foot the bill for Catholic, Jewish, Muslim, Hindu and evangelical Christian schools, among others, alongside public schools. The ruling will then be pushed in other states. It will be a rejection of the nation’s founders’ beliefs in the separation of church and state and will open the door to endless demand for government dollars from religious entities.

Public schools have been funded by public funds for centuries. Private and religious schools have financed their decision to part ways with the public system. Now, St. Isidore is demanding a piece of the pie as it claims that it would be discriminatory to leave it out of taxpayer support.

While I agree religions can’t be targeted or discriminated against, the court and the religious right have inflated the notion of discrimination to wipe out the basic constitutional notion of separation of church and state. This case invites the court to end the core tenet.

Like many U.S. Supreme Court cases, St. Isidore’s is the vanguard for a movement — in this case a movement that has argued that it is discriminatory to permit charter schools for secular reasons but not religious ones. It has been encouraged by the conservative cast of the justices overall, who have recently departed from James Madison’s warning about forcing taxpayers to financially support believers’ religious education through taxation.

In his “Memorial and Remonstrance,” Madison — the author of the First Amendment’s guarantee of freedom of religion and the establishment clause — argued that letting taxpayer dollars support religious education leads to division and religious establishments like those that enforced religious orthodoxy in Europe at the time. Our establishment clause doctrine was built on Madison’s caution that government-funded religion can corrupt both the government and religion. 

In 1947’s Everson v. Board of Education, the Supreme Court held that a state could provide busing to all students, even those going to religious schools (primarily parochial schools), but warned that further support would violate the separation of church and state. But that case turned out to be just the beginning of religious lobbyists seeking government support for every aspect of their schools and missions.

For decades, the court employed the “Lemon test” — named after Alton Lemon, the lead plaintiff in another case — which again rested on the idea that uniting church and state is inherently dangerous. It required courts to examine government support of religion, including funding, under three categories: The government’s policy must serve a secular purpose, the primary effect must neither advance nor inhibit religion, and there can be no excessive entanglement. Essentially, it held Madison’s line.

Those days are over, as the conservative justices have replaced the Lemon test with an elastic “equality” doctrine they echoed at oral argument. The religious right’s Alliance Defending Freedom advocacy group explained its discrimination-centered position on St. Isidore as follows:

“Oklahoma parents and children are better off with more educational choices, not fewer,” said ADF chief legal counsel Jim Campbell. “The U.S. Constitution protects St. Isidore’s freedom to participate in Oklahoma’s charter-school program, and it supports the board’s decision to provide more high-quality, no-cost educational options for Oklahoma families. The government can’t invite a vast …. array of groups to participate in its charter-school program while singling out religious groups for exclusion.”

In other words, there are just two choices if the case is decided along the group’s “discrimination principles”: Religious schools get full taxpayer support, including for religious instruction, religious employees and worship, or the government has to eliminate charter schools altogether.

The court has created a pathway for religious entities to belly up to the government’s funding bar by reasoning that religious education is no different from secular or other religious uses. But is that true? 

For Madison and the founders, when Protestants or Catholics shared power with governments in Europe, the result too often was vicious tyranny. The same was true when Puritans and Congregationalists in Massachusetts were established, and sidelined and persecuted Baptists and Quakers. Separation in the United States has long been intended to forestall the sticky, dangerous power-sharing that’s now part of the Christian nationalist vision encoded in the Heritage Foundation’s Project 2025, which the Trump administration has been using as a playbook. This case is one front in the war on our religiously diverse society.

As history has proved, religion is more than capable of partnering with authoritarians. It’s simply a fact that religious schools will impose their beliefs on students with crucifixes in every room, worship from their canon and teachers preaching against abortion, contraception and LGBTQ rights. 

There should be a constitutional difference between publicly funding a religious charter school and a drama charter school. That’s because the former drenches education in a single faith, while the latter brings a multitude of believers and nonbelievers together without reference to their faith. The latter is what makes our public school system the mortar that holds together a society of diverse religious groups.

Government support of the inherent coercion of religious schooling could be the end of the establishment clause discussion. A Supreme Court decision refusing to further the transmogrification of “equality” by religious actors could halt this American experiment in its tracks. But I heard only Justices Sonia Sotomayor, Elena Kagan and Ketanji Brown Jackson stand up for the religious liberty and separation that support our religious diversity. 

Buckle your seat belts for higher school taxes as religious schools line up to force taxpayers to support them in addition to public, secular school systems and charters. One alternative could be that states choose to eliminate charter schools altogether, though I’m not persuaded that will stop this drive to amass taxpayer-sourced wealth by religion. In the religious right’s universe, this is merely a step toward the ultimate goal of shifting school taxes away from public schools to their own coffers.

(Marci A. Hamilton is a constitutional law professor at the University of Pennsylvania and a Fox Family Pavilion Senior Fellow in the Program for Research on Religion. The views expressed in this commentary do not necessarily reflect those of RNS.)