Who are these people and why are they "Nones"? Peter Beinert (my emphasis)
In the mid-20th century, liberals were almost as likely to attend church as conservatives. But starting in the 1970s, when the Religious Right began agitating against abortion, feminism, and gay rights, liberals began to identify organized Christianity with conservative politics. In recent years, the Religious Right's opposition to gay marriage has proved particularly alienating to Millennials..... Today,according to Pew, the religiously unaffiliated are disproportionately liberal, pro-gay marriage, and critical of churches for meddling too much in politics. Not coincidentally, so are America's young.
What is growing in contemporary America, in other words, is something long associated with Europe: anticlericalism. In Europe, noted the late political scientist James Q. Wilson in a 2006 essay on American exceptionalism, the existence of official state religions led secularists to see "Christians as political enemies." America, Wilson argued, lacked this political hostility to organized religion because it separated church and state. But today, even without an established church, the Religious Right plays such a prominent and partisan role in American politics that it has spurred the kind of antireligious backlash long associated with the old world. Barack Obama is the beneficiary of that backlash, because voters who say they "never" attend religious services favored him by 37 percentage points in 2008 and 28 points in 2012. But he's not the cause. The people most responsible for America's declining religious exceptionalism are the conservatives who have made organized Christianity and right-wing politics inseparable in the minds of so many of America's young.Oh well done, conservatives. Well (over-) played.