American people, especially the young, are increasingly losing their religious faith judging by an apparent reduction in church attendance, prayer and belief in God, a poll shows.

The number of US adults who say they believe in God dropped to 89 percent in 2014 from 92 percent in 2007, according to the Pew Research Center's Religious Landscape Study released on Tuesday.

There was a decrease in the proportion of Americans who are "absolutely certain" that God exists and it fell to 63 percent in 2014 from 71 percent in 2007.

Also, the percentage of Americans who pray every day, attend religious services on a regular basis and consider religion significant in their lives dipped, the survey found.

Among the young adults, only half of those born from 1990 to 1996 are absolutely certain of their belief in God, in comparison with 71 percent of the "silent generation," or those born from 1928 to 1945.

In addition, younger people are more unlikely to pray daily, at 39 percent, compared to "silent generation" adults, standing at 67 percent.

Young adults are also less keen on attending religious services, according to the survey.

There are religious divides among the political parties, with 28 percent of Democrats and 14 percent of Republicans not religiously affiliated.

Both the 2007 and 2014 polls surveyed over 35,000 adults and had margins of error of less than 1 percentage point.