The term porneia is a Greek term that has two basic meanings:
1. Sex with a prostitute; prostitution.
2. Sexual immorality in general.
The issue for biblical studies is two-fold: (1) which meaning is in view in this text? and (2) what does the sexual immorality in general mean?
If one thinks a given NT text (say Matthew 5:32) is sexual immorality in general, and we are looking at a Jewish speaker (which Jesus was), then we are driven to one classic defining text in the Jewish world that defines sexual immoralities for the Jew, namely, Leviticus 18. In other words, if you double-click on the Greek term porneia for a definition, it sends you to Leviticus 18’s delineations. Here it is:
Lev. 18:1 The LORD said to Moses, 2 “Speak to the Israelites and say to them: ‘I am the LORD your God. 3 You must not do as they do in Egypt, where you used to live, and you must not do as they do in the land of Canaan, where I am bringing you. Do not follow their practices. 4 You must obey my laws and be careful to follow my decrees. I am the LORD your God. 5 Keep my decrees and laws, for the person who obeys them will live by them. I am the LORD.
Lev. 18:6 “ ‘No one is to approach any close relative to have sexual relations. I am the LORD.
Lev. 18:7 “ ‘Do not dishonor your father by having sexual relations with your mother. She is your mother; do not have relations with her.
Lev. 18:8 “ ‘Do not have sexual relations with your father’s wife; that would dishonor your father.
Lev. 18:9 “ ‘Do not have sexual relations with your sister, either your father’s daughter or your mother’s daughter, whether she was born in the same home or elsewhere.
Lev. 18:10 “ ‘Do not have sexual relations with your son’s daughter or your daughter’s daughter; that would dishonor you.
Lev. 18:11 “ ‘Do not have sexual relations with the daughter of your father’s wife, born to your father; she is your sister.
Lev. 18:12 “ ‘Do not have sexual relations with your father’s sister; she is your father’s close relative.
Lev. 18:13 “ ‘Do not have sexual relations with your mother’s sister, because she is your mother’s close relative.
Lev. 18:14 “ ‘Do not dishonor your father’s brother by approaching his wife to have sexual relations; she is your aunt.
Lev. 18:15 “ ‘Do not have sexual relations with your daughter-in-law. She is your son’s wife; do not have relations with her.
Lev. 18:16 “ ‘Do not have sexual relations with your brother’s wife; that would dishonor your brother.
Lev. 18:17 “ ‘Do not have sexual relations with both a woman and her daughter. Do not have sexual relations with either her son’s daughter or her daughter’s daughter; they are her close relatives. That is wickedness.
Lev. 18:18 “ ‘Do not take your wife’s sister as a rival wife and have sexual relations with her while your wife is living.
Lev. 18:19 “ ‘Do not approach a woman to have sexual relations during the uncleanness of her monthly period.
Lev. 18:20 “ ‘Do not have sexual relations with your neighbor’s wife and defile yourself with her.
Lev. 18:21 “ ‘Do not give any of your children to be sacrificed to Molek, for you must not profane the name of your God. I am the LORD.
Lev. 18:22 “ ‘Do not have sexual relations with a man as one does with a woman; that is detestable.
Lev. 18:23 “ ‘Do not have sexual relations with an animal and defile yourself with it. A woman must not present herself to an animal to have sexual relations with it; that is a perversion.
Lev. 18:24 “ ‘Do not defile yourselves in any of these ways, because this is how the nations that I am going to drive out before you became defiled. 25 Even the land was defiled; so I punished it for its sin, and the land vomited out its inhabitants. 26 But you must keep my decrees and my laws. The native-born and the foreigners residing among you must not do any of these detestable things, 27 for all these things were done by the people who lived in the land before you, and the land became defiled. 28 And if you defile the land, it will vomit you out as it vomited out the nations that were before you.
Lev. 18:29 “ ‘Everyone who does any of these detestable things—such persons must be cut off from their people. 30 Keep my requirements and do not follow any of the detestable customs that were practiced before you came and do not defile yourselves with them. I am the LORD your God.’ ”