A new survey finds that cohabitation is pervasive in the United States, and is increasingly viewed as acceptable by Christians—even if it doesn’t lead to marriage.

Here is what you should know—and that most American don’t—about cohabitation.

1. Cohabitation is the state of living together and having a sexual relationship without being married. Because Scripture considers all sexual activity outside the covenant bonds of marriage to be sexual immorality, cohabitation is sinful and should be rejected by orthodox Christians (Acts 15:20; 1 Cor. 6:13, 18; 10:8; 2 Cor. 12:21; Gal. 5:19; Eph. 5:3; Col. 3:5; 1 Thess. 4:3; Jude 7).

2. As more U.S. adults are delaying or foregoing marriage, the percentage who have engaged in cohabitation has been rapidly increasing. Since the 1960s, the percentage of men and women who cohabit before marriage has increased by almost 900 percent. More recently, Pew Research found that the share of adults ages 18 to 44 who are living with an unmarried partner has risen from 3 percent in 2002 to 7 percent in 2017. But a report by the CDC’s National Center for Health Statistics that selected only adults who had sexual intercourse with a partner of the opposite sex, found the numbers were even higher: 17.1 percent of women and 15.9 percent of men were cohabiting.

3. Among adults ages 18 to 44, the share who have ever cohabited (59 percent) is now larger than the share who have ever been married (50 percent). Young adults (ages 18 to 29) are almost twice as likely to have cohabited as they are to have married (44 percent vs. 23 percent). Among those ages 30 to 44, the share that has cohabited (71 percent) is similar to the share that has married (73 percent), and 52 percent have both cohabited and married at some point. A majority (62 percent) of adults ages 18 to 44 who have ever cohabited have only ever lived with one partner. About one-in-four (24 percent) have had two cohabiting relationships over the course of their life, and 14 percent have had three or more partners.

4. Almost all of the increase in non-marital births in the United States since 1980 has taken place in the context of cohabiting unions. Most adults ages 18 to 44 who are presently cohabitating are also living with children. In 2018 an estimated 5.8 million American children lived with cohabiting parents, which accounts for about 8 percent of all children younger than 18. Among cohabiters, 54 percent have at least one child 18 or younger at home, compared to 77 percent for married adults. A majority of Americans say that married and cohabiting couples can raise children equally well, even though social science research has shown that is not true. For example, research has found that children who live with their own cohabiting parents are more likely to suffer abuse. According to the Fourth National Incidence Study of Child Abuse and Neglect, children living with biological cohabiting parents are more than four times as likely to be emotionally, physically, and sexually abused as children living with their own married parents. “Cohabitation is also associated with greater family instability, as most cohabitations in the U.S. are short lived,” family researcher Wendy Wang says. “And family instability, in turn, is strongly linked to poorer child outcomes. Nevertheless, more and more children today find themselves living in a cohabiting family—at least for a time.”

5. Most Americans (69 percent) find it acceptable for an unmarried couple to live together, even if they don’t plan to get married. Another 16 percent say it’s acceptable, but only if the couple plans to marry. Only 14 percent say cohabitation is never acceptable. Younger adults are more likely than their older counterparts to find it acceptable for an unmarried couple to live together. About eight-in-ten adults younger than age 30 (78 percent) say cohabitation is acceptable even if the couple doesn’t plan to marry, compared with 71 percent of those ages 30 to 49, 65 percent of those 50 to 64, and 63 percent of those 65 and older.

6. White evangelicals and black Protestants are the least likely to say that it’s acceptable for an unmarried couple to live together even if they don’t plan to get married. Still, more than one-in-three white evangelicals (35 percent) and almost half of black Protestants (47 percent) consider this form of sexual immorality to be acceptable. Roughly three-quarters of Catholics (74 percent) and white Protestants who do not self-identify as born-again or evangelical (76 percent) say the same.

7. Cohabiting adults report much lower levels of relationship stability than do married adults. Married adults also express higher levels of satisfaction with their relationship, and are more likely than those who are cohabiting to express a great deal of trust in their spouse or partner is being faithful to them, will act in their best interest, always tell them the truth, and will handle money responsibly. Additionally, married adults are much more likely than cohabiters to say they feel closer to their spouse or partner than to any other adult. About eight-in-ten married adults (78 percent) say they feel closer to their spouse than to any other adult in their life, compared to a mere majority (55 percent) who say the same about their cohabitating partner.

8. Cohabiting couples report more depression and more alcohol problems than married couples. “Even when controlling for race, age and gender, cohabiting individuals reported higher levels of depression than married ones, 2.8 points according to one study,” Caitlin Thomas notes. “In another study, cohabiting individuals were three times more likely to report having problems with alcohol consumption than those who were married, as well as 25 percent more problems than single people who did not cohabit.” Cohabiting women also reported having more alcohol problems than married women, and men who cohabited said they had more alcohol problems than both married and single men.

9. Roughly half of Americans (48 percent) say that, compared with couples who don’t live together before marriage, couples who do live together first have a better chance of having a successful marriage. But research shows the opposite is true. While living together before marriage is associated with lower odds of divorce in the first year of marriage, cohabitation increases the odds of divorce in all other years. “Those who go straight into marriage without living together have a bigger immediate shock to negotiate after marriage, and as a result, have a short-term increased risk that’s greater than those already living together,” family scholar Scott Stanley says. “But that’s short-term, and the risk remains long-term.” Overall, cohabitating couples who marry are about 33 percent more likely to get divorced than couples who did not live together before marriage.