A fully taxable church would have to pay income tax on all contributions less deductible business expenses, would pay property and sales tax from which now currently exempt, and couldn’t offer donors a tax deduction.
African American churches would be far less effected, by the way.
The typical African American church derives most of its revenue from its dual status as a conduit for government social service dollars. What’s left in its budget it funded by donors far less likely to itemize deductions. It usually occupies low value real estate.
Also, they deal in cash, and keep no records. You'd be shocked how many blacks don't have checking accounts. Hard to collect for back taxes if there's nothing written down.