Religious affiliations in America are changing rapidly. Between 1990 and 2001 the proportion of United States citizens without religious affiliations apparently rose from 8% to 14%, while adults believing in Christianity dropped by 1% per year during the same period. Evangelicals are losing 20-30% each generation.  Should this decline continue over a generation, the United States will change dramatically.
This is all good news because secular democracies tend to do better than more religious nations.    Not all those without religious affiliations are Atheists, Agnostics, Freethinkers etc but quite a number are. In particular young people are more frequently without religion. 
As a consequence, a “siege mentality” may be developing among the Christians, leading many to try and deny free speech to those who so persuasively discourage fellow Americans from being Christians. Does the United States Constitution allow this? Prejudice against atheists is increasing, atheists are accused of being shrill, of New atheism if we promote our views the way believers feel free to promote their beliefs. The majority of American Christians realize there are fewer Christian round them and the opinion leaders - those who influence active church goers - are likely to know even more. Fortunately as the proportion of American Christians declines Christians will less be able to cause problems for atheists and other Non-Christians. Young atheists should face steadily reducing trouble from Christian intolerance as the decades progress. 
Young Americans in the 18 to 25 age group are more likely to accept Evolution. Among Americans over 40 the majority believe in creationism. Young Americans are less likely to go to church; the decline in Christianity is happening mainly as each new generation is less inclined to be religious or to believe in God. Some deconversions happen among older people as well though. As the proportion of atheists increases, ordinary people will increasingly get to know atheists and will increasingly see that we are moral. Actively promoting Humanist morality and showing that we are trustworthy human beings may help reduce prejudice.
Some deconversions in the United States and elsewhere happen because atheists show believers their faith is irrational but most happen because people see this for themselves. Adults, even intelligent older children and young teenagers, if they hear or read a non-Christian folk tale, piece of mythology treat it as fiction. When people have been told persuasively from early childhood to believe the bible not all see the similarity between biblical and other mythology but increasing numbers see this. Shrill atheism may increase the rate of deconversion marginally, it certainly makes atheists more confident. Even if New Atheism were to stop (which is unlikely) the steady erosion of Christian faith will continue.
- Atheism and the Internet
- Can Decline in religious belief improve society?
- New atheism
- Religious belief in the UK UK citizens who actually believe that Jesus existed and was special are a minority. Will the USA be like that in a generation?
- A movement of the irreligious
- Researcher of religion’s link to social ills comes under withering attack
- Too much religion may be a dangerous thing.
- Cross-National Correlations of Quantifiable Societal Health with Popular Religiosity and Secularism in the Prosperous Democracies: A First Look
- Secular Americans: Freethinkers in a Free Market of Religion
- The Bible Belt sometimes shifts culturally in a different direction from the rest of the United States and it's not so clear what will happen there. We guess the Internet will get through to them and the Bible Belt will finally follow the rest of the USA.
- The Largest Atheist / Agnostic Populations This Site tells the proportion of non-believers throughout the world including the United States.
Note: More than one survey suggest this.
- Growing Atheist Movement in America Even Fox News tries to come to terms with the fact that there are more non-believers in the United States.
- Millions are Living Happily Without Religion