Last night, at a CNN candidate forum on gay rights, CNN's Don Lemon asked Democratic candidate Beto O'Rourke: "religious institutions like colleges, churches, charities. Should they lose their tax-exempt status if they oppose same-sex marriage?"
O'Rourke answered "Yes," going on to say "There can be no reward, no benefit, no tax break for anyone ... that denies the full human rights and the full civil rights of every single one of us."
Aside from being grossly illiberal, anti-pluralist, and inflammatory, O'Rourke's announced policy is also unconstitutional under current Supreme Court precedent.
As a long line of court opinions has made clear, to quote Eugene Volokh, "tax exemptions can’t be denied based on the viewpoint that a group communicates," and the law “may treat groups differently based on their actions, but not based on the views they express” (emphasis added). "Support," the term used in the question, makes clear that viewpoint and doctrine are at issue here.
Whether through tax leverage or other means, the Constitution also forbids government from reaching into many internal decision processes of churches. The Supreme Court rebuked the Obama administration on this in the 2012 Hosanna-Tabor case, 9-0. Every single liberal Justice joined in defense of church autonomy in that case.
To be sure, there are ways consistent with the Constitution to curtail the tax exemption of churches or religious organizations, but they might require curtailing that of pro-gay or progressive churches on the same neutral basis. Complicating matters, much of the tax exemption of religiously oriented colleges, hospitals, social service agencies, etc. amounts to the same tax treatment that would be accorded secular nonprofits that do the same things.
The one big anomaly in this field of law is the Burger-era Bob Jones University case of 1983, in which the Supreme Court upheld the IRS's denial of exemption to a religious college that maintained rules against interracial dating. (Note that this denial was based on the college's actions, as opposed to its doctrine or its failure to "support" a public orthodoxy.) Some at the time predicted that the next to fall under the same logic would be exemptions for colleges and church groups that discriminate on the basis of sex in student admission or the selection of clergy. Thirty-six years on, nothing of the sort has happened. Perhaps the best explanation is that race is sui generis in American law, and accepted by courts as grounds for interventions they would otherwise reject.
The position on taxation of religious institutions to which O'Rourke assented Thursday evening is extremist and oppressive.