When leaders of traditional faith groups think about reaching out to Millennials, religious seekers, unaffiliated "Nones" and other postmodern young Americans, this is the voice that many keep hearing in their heads.

"Morality is how I feel too, because in my heart, I could feel it," said one person interviewed in the National Study of Youth and Religion. "You could feel what's right and wrong in your heart as well as your mind. Most of the time, I always felt, I feel it in my heart and it makes it easier for me to morally decide what's right and wrong. Because if I feel about doing something, I'm going to feel it in my heart, and if it feels good, I'm going to do it."

Seconds later, young people caught up in what experts now call "emerging adulthood" may stress that they are open to attending multigenerational congregations that offer roots, tradition and mentors. But how will they know when they have found the right spiritual home?

Right. When they feel it.

That's a hard target to hit, said Naomi Schaefer Riley, author of "Got Religion? How Churches, Mosques and Synagogues Can Bring Young People Back." Many religious leaders are struggling to find a "sweet spot between deep religious messages that sound cool" and faith that "seems like it comes from a sappy self-help book," she noted.

In light of current trends, it's also hard for clergy to take comfort in the trend seen in previous generations, which is that young people who abandon the pews usually return when they are married and have children. Trouble is, increasing numbers of Americans between 20 and 40 are delaying marriage, family and any community ties that bind. Some are opting out of marriage altogether.

This creates strong moral tensions.