More than half of Americans believe God has a special relationship with the US, a new poll has revealed.

In total, 53 per cent of 1,000 people surveyed agreed with the statement that God has a special relationship with America; a figure that rose to 67 per cent of evangelical Christians.

African Americans were also among the most likely to share the belief, at 62 per cent, along with 59 per cent of Southerners.

"'God bless America' is more than a song or a prayer for many Americans. It is a belief that God has blessed America beyond what is typical for nations throughout history," explained Ed Stetzer, executive director of LifeWay research. "I am sure that would spawn many theological conversations."

Stetzer added that those who live in certain areas or are part of religious groups "are most likely to believe in this special relationship.

"But, considering the history of the nation, from Manifest Destiny to Ronald Reagan's 'City on a Hill' speech, it's not surprising this long-held theme continues today."

An earlier survey released by LifeWay last month found that though studies suggest Christianity in America is in decline, the majority of those who don't identify with any faith are still open to church. Recent data also found that teens and young adults are both less religious and less spiritual than previous generations.

A study compiled by experts including Jean Twenge of San Diego State University concluded that Millennials are less likely to say religion is important in their lives and spend less time praying or meditating.