Question: What is fornication?
Answer: In a biblically illiterate society, many Bible terms either loose their meaning or have them replaced. "Fornication" is a classic example.
The biblical meaning of fornication. The Greek word translated "fornication" is porneia. Porneia is found 26 times in the Greek New Testament. W. E. Vine states porneia (fornication) "is used of illicit sexual intercourse...." (Expository Dictionary of New Testament Words). Henry Thayer defines "fornication" as "illicit sexual intercourse in general...distinguished from adultery (moicheia) in Matt. 15: 19...used of adultery...in Matt. 5: 32, 19: 9 (Thayer's Greek-English Lexicon, pg. 532). The granddaddy Greek work says of fornication, "The N. T. is characterized by an unconditional repudiation of all extra-marital and unnatural intercourse" (Theological Dictionary of the New Testament, Vol. 6, pg. 590).
Illicit sexual intercourse. As you can see from the definition of porneia, all illicit sexual intercourse is condemned. Illicit sexual intercourse is that involving a married man with one other than his wife or sexual intercourse between two unmarried people (Matt. 5: 32, 1 Cor. 7: 1 ff). Sinful sexual intercourse can and does include sodomy or homosexual activity (Jude 7, cp. Gen. 19).
Beloved fornication is a work of the flesh (Gal. 5: 19). We are to abstain from fornication and not use our body for fornication (1 Cor. 6: 18, 13). Fornication is the only acceptable reason for divorce and remarriage (Matt. 5: 32, 19: 9). Corruption and filthiness are associated with fornication (Rev. 17: 4; 19: 2). Moreover, those who fornicate can not go to heaven (1 Cor. 6: 9).
There is no doubt about it, pre-marital, extra-marital, those in unscriptural marriages, and all who engage in unnatural sexual intercourse are committing fornication (1 Cor. 7: 1 ff.; Matt. 5: 32; 19: 9; Jude 7).