My theory is the numbers have been inflated by the deceived Christians who believe they are Christian only because they attend Church on Sunday. Add a little sacrifice and it separates the chaff from the wheat.
In my opinion, there are more alternatives today, simply more activities one has access to. Not only on Sunday, but throughout the week the average family with kids stays busy, continuously on the go with sports and school related activities. More divorce, more single parents, more shuffling kids around on weekends, more stepchildren, etc. exacerbates the busyness. Come Sunday, they are just too darn tired to go to church. Most mistakenly associate Christianity with Church, because with them, it ends there. They were never Christians at all.
