Over 75 percent of Americans still identify themselves as Christians, according to a recent Gallup poll. Among them, more than 50 percent say they belong to non-Catholic and Protestant groups, some 20 percent are Catholics, and another 2 percent identify with minor sects.

The religious identities recorded by the poll in the interviews with about 174,000 people show a 5 percent drop in Christian affiliations.

Some 20 percent of the participants did not have any religious identification, a figure that is up from 15 percent in 2008. About 5 percent of the respondents adhered to a different belief system.

"Despite these changes, America remains a predominantly Christian nation, and with 94% of those who identify with a religion saying they are Christian," the poll says.

The elderly were more likely to affiliate themselves with Christianity when compared to the younger generation, according to the poll.

However, the percentage of young population that identifies with Christianity still remains high, as 62 percent in the age group of 18 to 24 said they were Christians.

About 79 percent of the people aged between 45 and 49 said they adhered to the faith, while as many as 88 percent of Americans in the age group of 85 to 89 years believed in Christianity.

"These results are based on interviews conducted each year since 2008 as part of Gallup Daily tracking. The general trends in the data over this eight-year period are clear: As the percentage of Americans identifying with a Christian religion has decreased, the percentage with no formal religious identification has increased," said Frank Newport, writing for Gallup report.

A similar report by Pew Research Center earlier in 2015 showed that a high proportion of those who affiliated themselves with no religion were not highly educated and fell in lower-income socioeconomic brackets. Religious "nones" constituted only about 24 percent of college graduates, while 64 percent of college-educated Americans identified themselves as Christians.

The report concluded noting that "more than 95% of Americans identified as Christian in the 1950s, and 80% did so as recently as eight years ago. While the 5% of the population who identify with a non-Christian faith is higher than it was decades ago, it has not shown significant change over the past eight years."