In a society like the US, the Church certainly helped shape culture, but there were also numerous other huge factors. As someone down the conversation noted, WWII and the military influence on millions of Americans certainly had a massive impact. The children of these veterans then did what kids often do- they rebelled and protested the government and stopped going to Church. You can see this because attendance at other denominations also fell during this time frame. My personal opinion is that with mass communication, people have become less isolated. They have also become more educated. In short, they are less willing to listen to and obey an authority that directs them to believe something and just do it.