James L. Haught has posted on the continued rise of secularism in the United States A Huge News Story, Barely Noticed | Unreasonable Faith. In much of Europe, Canada, Australia, and Japan, the fraction of worshippers has dropped to 5-10%, but the US continues to lag behind this trend, with its megachurches and TV evangelists.
But the US has been belatedly following along. “Nones” have been rising from 8% in 1990 to 15% in 2008, Catholics and mainline Protestants have been declining, and young people have been dropping out of organized religion at 5 or 6 times their historic rate.
James Haught notes that this trend will likely hurt the Republican Party and help the Democratic Party, because of how more secular voters tend to vote, but I suspect that the Republican Party may try to adjust its message to appeal to more secular voters.