Q. Where does Scripture say that people should not live together before marriage?
A. The Greek New Testament word translated into English as “fornication” or “sexual immorality” or sometimes just “immorality” (porneia — from which we get the word “pornography”) refers sometimes to sexual relations between unmarried persons, and sometimes to that kind of sexual activity as well as adultery. In either case, the term always includes the meaning of sexual relations between unmarried persons.
Given that definition, we can find cohabitation prohibited or condemned in a number of biblical passages, such as Matthew 15:19; Mark 7:21; Acts 15:20, 29; 1 Corinthians 5:11; 6:9-10, 18-20; 7:1-2; 10:8; 2 Corinthians 12:21; Galatians 5:19; Ephesians 5:3; Colossians 3:5-6; 1 Thessalonians 4:3-8; and Revelation 21:8, 22:15.