It’s the other tax-exempted groups that should worry, and do.
Repeal section 501(c). End tax exemptions. Make the Clinton Foundation, the Pew Foundation, Planned Parenthood -- ALL of the "non-profits" that employ so many Leftists -- make them all subject to corporate tax like any other corporation.
As for the churches, they don't need buildings. Go back to the roots of the early Church. They can rotate meeting in people's living rooms.