Now, more than ever, Christians, especially parents, have a great responsibility to keep the faith among the youth.

A recent survey by the Public Religion Research Institute (PRRI) revealed that 25 percent of the American population consider themselves not affiliated with any religion.

The same polls showed that almost two in every five Americans aged 18 to 29 do not have any religion. That's the highest among age groups in the survey.

Twenty-nine percent of Americans aged 30 to 49 are not religiously affiliated, while 17 percent of those aged 50 to 64 say they do not have any religion. Thirteen percent in the 65-and-above age group are also religiously unaffiliated.

While there was an increase in the number of individuals without religions across all age groups, the rise was most pronounced in Americans aged 18 to 29. During the last PRRI survey in 2006, only 23 percent from this age group said they were religiously unaffiliated.

What made them leave organised religion? In a report from Religion News, PRRI Research Director Daniel Cox explained that it is less about being offended by religious groups' treatment of some sectors like homosexuals but more about simply stopping to believe in religious teachings.

"Those things matter but they are dwarfed by this central idea that people no longer believe in religious teachings," he said.

In fact, 60 percent of those who left organised religion simply "stopped believing" in the faith they were exposed to beginning childhood. The PRRI also revealed that most of the respondents said they stopped believing before reaching the age of 30.

Thirty-two percent meanwhile said they became religiously unaffiliated because their family did not have much religious commitment. Less than a third cited negative teachings about homosexuals as reason for leaving religion, while 19 percent cited sexual abuse cases involving the clergy.