According to the U.S. Churches Database, there exist 68,574 churches in the United States, of which 1,210 are megachurches (defined as having a seating capacity of over 2,000). We will assume, generously, that the average maximum occupancy of a megachurch is 10,000, for a total of 12,100,000 seats. Ignore for a moment the fact that a study conducted this year by the evangelical Christian Outreach Magazine tracking the biggest 100 churches in the U.S. puts their total weekly attendance at just 631,585. It is mathematically impossible for all 1,210 megachurches to have over 6,000,000 attendants per week, but, for the sake of erring on the side of caution, we'll go with 12,100,000.
The remaining 67,364 churches are medium- and small-sized operations, which can hold no more than 2,000 people, or they would have been included in the megachurch category. To accurately establish the average seating capacity for these remaining churches would be hard, but a guess of 200 seats per church seems fair, and one of 300 bounteous. Make it 400, but keep in mind that small-town churches, which needfully must comprise the majority of these sixty-seven thousand, are much tinier than that. Even with these grossly inflated numbers, the total seating capacity of non-megachurch establishments clocks in at 26,945,600. Add to that the 12,100,000 seats of the megachurches and we arrive at 39,045,600. Some large churches, though a minority, hold more than one weekly service; kindly insert 20,000,000 extra seats in our tally.
So, what is the maximum number of seats available at any given time in all of America's churches? Assuming that all are filled to capacity, that even the smallest of them can accommodate at least 400 people, and liberally adding 20,000,000 extra seats, the total number of available seats in churches across America is 59,045,600. That is just little over a half of what would be necessary to accommodate all the people who claim to go to church weekly. A large number of Americans are lying to the polls.