In his 1971 song "Imagine," John Lennon asks us to envision a secular utopia. There's no heaven, no hell. Peace and harmony reign, and a global "brotherhood of man" flourishes. Amid this blissful state of affairs, of course, we find "no religion."

Lennon was a talented songwriter, but when it came to theology, he was 180 degrees off. A world free of religion would certainly have no heaven. But there would be plenty of hell - and right here on earth.

This isn't simply the opinion of a lady who takes her faith seriously. A large and growing body of social science research shows what a huge difference religious faith makes in our everyday lives. It's no overstatement, in fact, to say that religion makes civil society possible. Without it, just about every indicator of human misery would be off the charts.

For a concise yet comprehensive catalog of just how bad things could be, take a look at a startling new paper by Pat Fagan, the Heritage Foundation's premier social-science researcher. In it, he sifts through countless studies that show the remarkable effect of religion on marriage, divorce, child-rearing, drug/alcohol abuse, out-of-wedlock births - even mental and physical health.

Start with an area near and dear to my heart - family relations. My husband and I have raised our three teenagers in a loving, religious household. Our faith in God has sustained us in good times and bad, and it has been a steady source of inspiration, comfort and encouragement. So I was particularly pleased to read the following in Fagan's paper:

Compared with mothers who did not consider religion important, those who deemed religion to be very important rated their relationship with their child significantly higher. … When mothers and their children share the same level of religious practice, they experience better relationships with one another. For instance, when 18-year-olds attended religious services with approximately the same frequency as their mothers, the mothers reported significantly better relationships with them, even many years later. … Moreover, mothers who became more religious throughout the first 18 years of their child's life reported a better relationship with that child, regardless of the level of their religious practice before the child was born.

The same holds true for fathers:

Compared with fathers who had no religious affiliation, those who attended religious services frequently were more likely to monitor their children, praise and hug their children, and spend time with their children. In fact, fathers' frequency of religious attendance was a stronger predictor of paternal involvement in one-on-one activities with children than were employment and income - the factors most frequently cited in the academic literature on fatherhood.

Couples are far more likely to stay together if they're religiously active, Fagan found. Indeed, the risk of divorce more than doubles for couples who stop practicing their religion. Religiously active couples also report greater happiness and satisfaction with their marriages. The incidence of domestic violence drops, too. Men who attended religious services at least weekly were more than 50 percent less likely to commit an act of violence against their partners than were peers who attended only once a year or less.

How about adolescent sexual behavior? Good news here, as well. Fagan notes that traditional values and religious beliefs were among the most common factors teens cite to explain why they are abstaining from sex. And religion affects out-of-wedlock childbearing: Compared with those who consider themselves "very religious," those who were "not at all religious" are two to three times more likely to have a child outside of marriage. In addition, the use of cigarettes and the abuse of alcohol and drugs drops significantly among those who are religiously active.

Religion is also a great help to those who never marry or have children. "A review of the research shows that religion significantly affects the level of an individual's happiness and overall sense of well-being," Fagan writes. "In the vast majority of the studies reviewed, an increase in religious practice was associated with having greater hope and a greater sense of purpose in life." In addition, people who are religiously active are at a much lower risk of depression and suicide. They also tend to live longer.

None of this would surprise our Founding Fathers, who knew that no people could be self-governing without religion. In his Farewell Address, George Washington referred to religion and morality as the "great pillars of human happiness" and noted: "Whatever may be conceded to the influence of refined education on minds of peculiar structure, reason and experience both forbid us to expect that national morality can prevail in exclusion of religious principle."

As you head to church this Christmas - and, I hope, in the weeks that follow - remember the indispensable role that religion plays in free society. We've been told by the highest authority, after all, that if we seek first the kingdom of God "all these things will be given to you as well." In a way, Jesus was telling us - almost 2,000 years before John Lennon wrote a single note - how to achieve a true "brotherhood of man." Imagine.

Rebecca Hagelin is a vice president of The Heritage Foundation and the author of Home Invasion: Protecting Your Family in a Culture that's Gone Stark Raving Mad.