When we talk of the United States, we often envision a country which is populated mostly by white Christians. However, this image of America is slowly fading away, according to recent study.

Robert P. Jones, founding chief executive officer of the Public Religion Research Institute (PRRI), recently published a new book entitled "The End of White Christian America," which detailed a surprising trend: the proportions of white, non-Hispanic Christians have declined across generations.

According to the data culled by Jones, only 29 percent of young adults aged 18 to 29 living in the United States identify themselves as white Christians.

This number is significantly lower compared when compared to past generations. Among seniors aged 65 and older, 67 percent said they are white Christians, while among those aged 50 to 64, 56 percent identified themselves as the same.

Also quite interestingly, the number of white Christians among young adults aged 18 to 29 is already almost the same as the number of non-white Christians, which was pegged at 28 percent of those surveyed.

"The American religious landscape is being remade, most notably by the decline of the white Protestant majority and the rise of the religiously unaffiliated. These religious transformations have been swift and dramatic, occurring largely within the last four decades," Jones said in an interview with The Washington Post.

The "disappearance" of white Christians in the United States is driving "strong, sometimes apocalyptic reactions" among members of this group, according to the researcher.

"Falling numbers and the marginalisation of a once-dominant racial and religious identity — one that has been central not just to white Christians themselves but to the national mythos — threaten white Christians' understanding of America itself," he said.

Jones added that while immigration is one of the factors that led to this decline, the younger generation's "rejection of organised religion" has also become evident.

"The rise of religiously unaffiliated Americans over the last few decades is one of the most important and dramatic shifts in American religious history," he explained.

The researcher further said that "there's no sign that this pattern will fade anytime soon."

"By 2051, if current trends continue, religiously unaffiliated Americans could comprise as large a percentage of the population as all Protestants combined — a thought that would have been unimaginable just a few decades ago," Jones said.