> They need to be taxed

> they can go around buying up assets until they own everything

The real estate transactions described in the article are purely income-generating rather than related to the mission of the church (e.g. for church buildings, temples); as such, any income from them is subject to income tax already under UBIT laws [1]. Same goes for local/state property taxes.

[1] https://www.irs.gov/charities-non-profits/unrelated-business...