The answer to this question depends somewhat on what is meant by “living together.” If “living together” simply means sharing the same house or apartment, with no sexual connotation, then, no, it is not technically wrong. Strictly speaking, there is nothing sinful about an unmarried man and an unmarried woman living in the same house or apartment, as long as there is no sex taking place.
However, that is not what is commonly meant by the term living together, which is often used as a euphemism for “having sex before marriage,” synonymous with shacking up. The Oxford Dictionary defines live together as “share a home and have a sexual relationship.” Rightly or wrongly, the sex is assumed.
For the purposes of this article, we will define living together or cohabiting as “sharing a home and having a sexual relationship.” Using that definition of living together, it is definitely wrong. Premarital sex is condemned in Scripture, along with all other forms of sexual immorality (Acts 15:20; Romans 1:29; 1 Corinthians 5:1; 6:13, 18; 7:2; 10:8; 2 Corinthians 12:21; Galatians 5:19; Ephesians 5:3; Colossians 3:5; 1 Thessalonians 4:3–5; Jude 1:7). The Bible promotes complete abstinence outside of (and before) marriage. Sex before marriage is just as wrong as adultery and other forms of sexual immorality because they all involve having sex with someone to whom you are not married.
We live in a world that is increasingly supportive of couples living together before marriage. According to a 2016 Barna study, the most common justification for living together is to evaluate compatibility (84 percent); other reasons include saving on rent (5 percent) and other practical considerations (9 percent) (www.barna.com/research/majority-of-americans-now-believe-in-cohabitation, accessed 9/15/21). This acceptance of living together is found even among practicing Christians, of whom 41 percent say cohabitation is “a good idea” (ibid.). In 2019, Pew Research found that 58 percent of white evangelicals approve of cohabitation if the couple plans to marry (cited in www.crosswalk.com/family/marriage/christians-and-cohabitation-what-you-need-to-know.html, accessed 9/15/21). Despite current trends that approve of living together, the Bible’s message stays the same: God forbids sex before marriage.
In addition to the biblical guidance are other sound reasons not to cohabit. The idea that living together is an appropriate “test-drive relationship” before committing to marriage falls apart under scrutiny. Contrary to the conventional wisdom, living together before marriage does not make a future marriage stronger. One study based on a national survey found that couples who had lived together were 46 percent more likely to divorce than other couples (DeMaris, A., and Rao, K. V., “Premarital Cohabitation and Subsequent Marital Stability in the United States: A Reassessment,” Journal of Marriage and Family 54, 1992, based on the National Survey of Families and Households, 178–190). Another study released through Rutgers University found that cohabiting is counterproductive to long-lasting marriages and recommended that unmarried couples avoid living together, especially if the arrangement involves children, due to the uncertainty and tenuousness of cohabitation (Popenoe, D., and Whitehead, B. D., “Should We Live Together? What Young Adults Need to Know about Cohabitation before Marriage,” The National Marriage Project, the Next Generation Series, Rutgers, the State University of New Jersey, 1999).
Even in the case of an unmarried couple who share a living space without having sex, some problems arise:
1) There is still the appearance of immorality. We must consider our testimony before an unbelieving world as we represent Christ. Most people naturally assume that a man and a woman sharing the same living space are sexually active. Even if the assumption is wrong, the implication remains. God calls us to a higher standard: “But among you there must not be even a hint of sexual immorality, or of any kind of impurity, or of greed, because these are improper for God’s holy people” (Ephesians 5:3). Living together definitely “hints” at sexual immorality.
2) Sharing a living space could be a tremendous temptation for immorality. Cohabiting couples, even if they commit to abstain from sex, are putting themselves in a position that can easily lead to compromise and allow the devil to tempt them. The Bible tells us to flee immorality, not expose ourselves to its constant temptations (1 Corinthians 6:18).
3) We have a responsibility to our brothers and sisters in Christ. The Bible’s admonition is that we do not cause anyone to stumble (Romans 14:19–21). It’s not enough to say, “We’re doing nothing wrong”; we must “pursue what makes for peace and for mutual upbuilding” (verse 19, ESV).
If a couple is living together outside of marriage, they have three basic options: (1) continue to live together; (2) find separate living quarters; or (3) get married now. Many couples choose to get married in a quick, private ceremony to make things “legal,” and then have a more formal, church-type wedding celebration later. Of those three options, (2) and (3) are the only godly choices.