And, independently of their tax status, they shouldn’t promote political candidates.

I don’t disagree with you on principle, but in practice, allowing the taxation of religious groups would create massive opportunities for abuse. Tax code can be structured to promote one religion and punish another, and you know for damn sure that our elected officials won’t hesitate to put their greasy thumbs on the scale.

Do they tax income? Investments? Real estate? Spending? Endowments? Salaries? Each of those would create a disparity in how much a specific group owes. Consider how the Mormons collect and spend money vs Catholics, or how Quakers don’t have preachers, just elders, while evangelical preachers earn hundreds of millions.

Any tax gives a massive advantage to the religions of the wealthy. You’d end up with four mega churches and a bunch of underground religious communities meeting in secret and sharing holy books smuggled in from Canada.

While I’d love to see churches start paying their fair share, I also see the way our tax code works now. We can’t get economic elites and the well connected to pay their fair share, what makes you think that it will happen with the religious economic elites and the religious well connected? It’s always the little people who suffer the most.

And regulated and inspected for abuses of power

My unpopular opinion is that people who keep throwing this stupid idea around have no clue what they’re talking about.

Religions / churches are non-profits. Their only revenue is post-tax donations. The people who work at the non-profit churches still pay income tax. The moment you start taxing a church, you allow them to function as a corporation. Not taxing churches is a fundamentally great thing.