Many people who say they have no religion are simply saying they have no official religious affiliation. They may actually have strong personal beliefs.
There are many critics who think the megachurches thrive on people who enjoy dramatic Sunday services with fine music but don't wish to become very 'religious' on a day-to-day basis - that the megachurch appeal is a mile wide and an inch deep.
The more members of the clergy that are out there working to expand their congregations, the more people will go to church.
American churches work very hard at reaching out to people to bring them in.
People value religion on the basis of cost, and they don't value the cheapest ones the most. Religions that ask nothing get nothing.
... One thing about religious truths is that we have to take them on faith, and faith needs reassurance. What's more reassuring than noticing that some other people, whom you admire, are so certain that it's all true that they're willing to go the ultimate mile?
The success of the West, including the rise of science, rested entirely on religious foundations, and the people who brought it about were devout Christians.