Citizens United did no such thing. There's a decades long history of case law from SCOTUS holding that speech cannot be constitutionally prevented because of the who the speaker is, the organization they belong to, or the viewpoint articulated (although, like all constitutional rights, that is not absolute).
Citizens United was more about how the speech was paid for and when exactly it could be exercised.
John Marshall held that the taxation cannot be used as an excuse to circumscribe the rights and powers bestowed in the Constitution.
I have no problem lifting 501(c)(3) politicking restrictions on all non-profits, not just churches.
These churches are correct. That legislation shouldn't stand up to judicial scrutiny.
If your read is ironclad, why is no one litigating this issue?
Here's an answer - because there is no right to tax exemption and churches are free to renounce their 501(c)(3) status and say whatever they want -- which I recommend.
§441b’s prohibition on corporate independent expenditures is an outright ban on speech, backed by criminal sanctions.
Less than two years after Buckley, <>Bellotti reaffirmed the First Amendment principle that the Government lacks the power to restrict political speech based on the speaker’s corporate identity. 435 U.S., at 784–785. Thus the law stood until Austin upheld a corporate independent expenditure restriction, bypassing Buckley and Bellotti by recognizing a new governmental interest in preventing “the corrosive and distorting effects of immense aggregations of [corporate] wealth … that have little or no correlation to the public’s support for the corporation’s political ideas.” 494 U. S., at 660. Pp. 25–32.
However, given its complexity and the deference courts show to administrative determinations, a speaker wishing to avoid criminal liability threats and the heavy costs of defending against FEC enforcement must ask a governmental agency for prior permission to speak. The restrictions thus function as the equivalent of a prior restraint, giving the FEC power analogous to the type of government practices that the First Amendment was drawn to prohibit.
Austin is overruled, and thus provides no basis for allowing the Government to limit corporate independent expenditures.