What would that even look like? Gift taxes are paid by the giver not the recipient. Currently you don't even have to report it if it's less than $18,000 per year per recipient. If you give less than $13 million in your lifetime you don't have to pay any gift taxes anyway.

I have a feeling that most people probably don't give $18,000 to their churches annually. At a 10% tithe rate, that's $180,000. Wel above the median household income.