The majority of white evangelical protestants in America don't believe the US is a Christian country, according to new research by the Public Religion Research Institute (PRRI).

More than half (59 per cent) of white evangelicals said they believe that the US is no longer a Christian country, up from 48 per cent in 2012.

The American public overall are divided on the issue. Forty one per cent said it was Christian and it still is, while 42 per cent believe it once was but is no longer. Just 15 per cent said the US has never been a Christian country.

The PRRI immigration survey produced in partnership with Brookings, released on Thursday, surveyed 2,600 adults between April 4 and May 2. It asked questions on how immigration and concerns about cultural change are shaping the 2016 election.

Almost half (49 per cent) of the American public said "discrimination against Christians has become as big a problem in America as discrimination against other groups".

Americans were divided over whether US culture is better now or in the 1950s.

"No group of Americans is more nostalgic about the 1950s than white evangelical protestants", according to the report. Seventy per cent said the country had changed for the worse in the last half-decade.

Across religious and political divides Americans are united in a belief that the country is moving in the wrong direction, with 72 per cent saying so. This is up from 65 per cent in 2011.

"When we step back and look at the big picture, we do see heightened anxieties among Americans," said PRRI CEO Robert Jones in a Washington press conference.