In denominational churches, fornication is often confused for idolatry, or it is defined as "sex before marriage". But in the Biblical view, the act of sexual intercourse between a man and a woman is the act of marriage  so there is really no such concept as "sex before marriage", and engaging in sexual relations, one is either 1) married, 2) getting married or 3) committing a forbidden act such as fornication, sodomy, or adultery.
Aside from other gratuitous sexual activities, such as prostitution or sodomy, the word fornication is used in Scripture to describe what may be called miscegenation, or race-mixing. This is evident in the epistle of Jude, in verse 7 where the King James Version has "7 Even as Sodom and Gomorrha, and the cities about them in like manner, giving themselves over to fornication, and going after strange flesh, are set forth for an example, suffering the vengeance of eternal fire."
While the Genesis account  attributes the act of Sodomy as a reason why Sodom, Gomorrah and the cities of the plain were destroyed, in that passage Jude further describes the people as having given "themselves over to fornication, and going after strange flesh", and the word for strange, ἑτέρος  refers to something other than or different from, or even other than usual . This use of the word is upheld by Paul of Tarsus in chapter 10 of 1 Corinthians, where he wrote in verse 8: "Neither let us commit fornication, as some of them committed, and fell in one day three and twenty thousand." The only occasion in Scripture to which he could have been referring is found beginning in Numbers chapter 25 where it says "1 And Israel abode in Shittim, and the people began to commit whoredom with the daughters of Moab."
- ↑ Gen. 24:67, 1 Cor. 7:9
- ↑ Gen. 18
- ↑ Strong's # 2087
- ↑ An Intermediate Greek-English Lexicon Founded Upon the Seventh Edition of Liddell and Scott's Greek-English Lexicon, H. G. Liddell and R. Scott, Oxford University Press, 1889, 1999, p. 321. See ἕτερος at the online Greek Word Study Tool at the Perseus Digital Library