In the modern western world, it can often be outright offensive to suggest that only actual penetrative sex (vaginal or anal) technically qualifies. One reason being it implies Lesbians can't have "actual sex" at all. But like it or not, for most of human history that has technically been the assumption. The Hebrew Bible doesn't have any word that simply translates to "sex" how we use it today. And there is plenty of evidence that in antiquity Lesbians took pride in being called virgins, looking at homo erotic myths related to Artemis/Diana and perhaps also Anath.
Biblical terms like "Lie with" or "Know" or "Uncovering Nakedness" are not strictly limited to sex in their literal definition anyway, so it's hard to determine without context.
The term "Lie Carnally" is more explicit, the word translated "Carnally" is Zera` [(zeh'-rah); Noun Masculine, Strong #: 2233] which means "seed", and can literally mean "sperm" or "semen". Technically the Strongs will give the impression in one occurrence that another word is what's translated Carnally. But that verse also uses Zerah, the order of words being changed in translation simply caused confusion here.
We tend to think of Carnally as meaning "fleshly" or "of the flesh". And in it's one New Testament appearance in the KJV of Romans 8, that is what the Greek word means there. But the Old Testament usages are different.
Now when a male orgasms his "Seed" comes out. So you might think that doesn't make it very specific at all. But in English we too have created a verb form of one of our terms for that substance. "Inseminate", and what we mean when we say "inseminate" isn't putting the semen anywhere, it's usually about putting your semen in a woman's reproductive organs making it possible a child could be conceived. Possibly with conception being the explicit intent. I think it's perfectly reasonable that Moses meant something similar, and that it's specifically reproductive sex those verses are about.
You may have heard of the principle that the Intent of the law is more important then the letter of the law, well that concept is in fact Biblical. Mark 2:27 "The sabbath was made for man, and not man for the sabbath". There is a reason for every law God gives, and the details are important because they help us understand the intent.
Only two not even potentially reproductive sexual acts are ever condemned. A very specific male homosexual act in a very specific pagan context. And Bestiality. Both initially occurring in Leviticus 18:22-23. Later verses are just repeating that commandment. The context of being after verse 21, as I've explained elsewhere means they're condemned because of Pagan rituals involving those acts.
The Bible also does NOT condemn Masturbation. That line you often hear (comedian Ron White says in one of his bits that his Grandmother quoted it to him) spouted which sounds Biblical, "It's better for thy seed to land in the belly of a whore to fall on the floor", really isn't, it's made up. In the Strongs you can easily tract down every occurrence of "Seed" as well as the other key words of that sentence (and synonyms for them), and it doesn't appear.
The story of Onan in Genesis 38 is the only basis people have for condemning masturbation, but it's not about that at all, Onan's Sin was breaking his agreement to produce offspring for his brother. And Masturbation isn't even what he did, but rather "pulling out".
Leviticus 15:16 has been cited as relevant to Masturbation. That is a part of Leviticus not about Sin at all but ritual uncleanness. Like being to close to a dead body.
When Jesus said in Matthew 5:28 "But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart." It is important first to know that the word translated "Woman" here is the Greek "Gune" which like the Hebrew "Ishshah" also means "Wife". In the context of being about adultery "Wife" is clearly the intended meaning here. That's still incidental to my point, though. People often cite that verse to sound like it means you've sinned every time you observe a woman's attractiveness, or get turned on, or simply don't immediately look away. That's not Jesus' intent, the intent is just to show that God judges thoughts as well as actions. But that doesn't mean being tempted itself is Sin. Jesus himself was Tempted and He's without Sin. It's indulging in those thoughts that makes it a Sin. He's really not introducing something new, but folding the Tenth Commandment into the earlier ones. Looking is fine, leering is not.
Now I've shown elsewhere that "Fornication" doesn't mean what you think it means, it means Prostitution.
The "Strange Woman" passages the occur throughout Proverbs are often cited by people as condemning any non-martial sex. The woman in question may or may not be a Prostitute of some form, but the greater point is that both words translated strange mean "alien" or "foreign", they don't mean bizarre or weird. And in these kinds of contexts it's being spiritually or religiously foreign, not ethnically or nationally that is the concern, (as we see with Ruth's marriage to Boaz being okay). Her not worshiping the True God is why she should be avoided.
It is popular for Christians to insist any non-reproductive sex is a sin, but that as you can see is not Biblical. In fact it has become my conclusion studying the Bible, that besides the Blasphemy of Pagan ritual sex acts, it's chiefly reproductive sex God desires to limit. Yes we were commanded to "Be Fruitful and multiply" but we are still supposed to do so carefully to give each new child a healthy stable family to raise them in.
The Song of Songs or Song of Solomon has three verses that poetically allude to what we today would label Oral sex. The woman on the man in 2:3, and the man on the woman in 4:16 and 8:2. The last of which is also proceeded by a verse describing the man suckling his lover's breasts.
Conservative commentators insist the Song of Songs only condones sexual activity between a husband and wife, because the book revolves around a marriage. But that ignores the chronology of the book, the wedding is in chapter 4, the end of chapter 4 is indeed the first allusion to actual intercourse, but they're Intimate in ways we'd today deem sexual well before then.
The idea that sex is only for reproduction is not Biblical, it is an expression of love, and also a basic physical need. Lack of moderation with anything can lead to problems and thus be sinful, since our Bodies are the Temple of God we should take care of them.
That basis for saying all sex outside Marriage, is an assumption that adultery being a sin, combined with the verses on the importance of virginity makes all extramarital sex a sin.
Number One, a woman who's already lost her virginity outside marriage is certainly not addressed, and in the culture of the time she was probably not going to get married. So should she be denied that pleasure for life based on one indiscretion? Which she might not have even consented to?
Number Two, what about a widow? Widows were allowed to remarry, that's the only time a non virgin could ever get married. And nothing directly condemning a widow having extra marital sex exists in The Law.
Number Three, how is adultery defined? First of all like it or not it only goes one way in the Biblical laws about it, (Even in the New Testament) only the woman's fidelity is addressed. Leviticus 20:10 "And the man that committeth adultery with another man's wife". Even in Matthew 5:28 condemning even the coveting there is no gender reversal equivalent.
It's undeniably unfair to women, but it was an unfairness necessary in the ancient world lacking DNA testing to verify paternity. And there are medical reasons why it's good to know your a kid's biological parents are, even though has nothing to do with the real definition of being a mother or father.
The actual wording of The Ten Commandments doesn't define adultery, just labels it a sin. It's Leviticus 18:20 and Numbers 5:12-13 that defines it, and the term used is "Lie carnally" (or "lie with her carnally") the definition of which I discussed on above.
Only one statement of Jesus, recorded in each Synoptic Gospel (it may be he said it more then once, since they seem to be at different chronological points), seems to imply a Man can commit Adultery against his Wife by being involved with another woman. Matthew 19:9, Mark 10:11 and Luke 16:18. "And he saith unto them, Whosoever shall put away his wife, and marry another, committeth adultery against her." But this passage exists in the context of condemning Divorce, and also remarriage after Divorce.
In the Sermon on The Mount when Jesus discuses the same matter, he possibly clarifies what he meant. Matthew 5:32 "That whosoever shall put away his wife, saving for the cause of prostitution, causeth her to commit adultery". Unlike Men, Women more or less needed to be married to survive back then, so when a man divorced his wife back then he forced her to remarry. So he's guilty of the sin of adultery because he forced someone else to commit it. Not because Jesus was suddenly defining Adultery in gender neutral terms no one ever heard of before.
"But it's also his taking another wife Jesus refereed to?" yo may respond. Regardless of what Jesus thought of Polygamy, even in Polygamous cultures most men were Monogamous because supporting more then one wife was difficult. So the man marrying a new wife means the chances of the rejected one being taken back are severely decreased.
So it's an old gender double standard that isn't as needed anymore because of modern technology. Yet modern society has chosen to try to make this double standard right by giving men the same restrictions women have always had. As a supporter of freedom, I think it should have been the opposite approach. The emotion of Jealousy is the basis for being so bothered by infidelity, Envy is a Sin.
Cheating is a Sin, but not a sexual sin, if it's part of the agreed terms of your relationship to be monogamous then yes failing to do so is a violation.
How is virginity defined? Many would argue it's absurd to purely base it on the modern clinical definition. I reject the traditional view of Tokens of Virginity. But again the implied intent came down to the man needing to know he's the father of any child conceived.
So basically, there is no Biblical Basis for condemning non Reproductive sex acts between unmarried indivduals.
In summery, Sex is only truly Sinful if it's motivated by something other then Love, or forced on someone against their will, or done in Pagan worship. But it is certainly preferred you try to avoid reproducing unless you know you can provide for the potential offspring.
I've seen one website (which argues many things I agree with) say that maybe sex outside marriage was fine under the Old Testament but not the New. Nothing is more wrong to me then suggesting the NT condemns something the OT doesn't. The things the OT tolerated that the NT doesn't seem to anymore like Harem Polygamy still had God's true disapproval apparent in the Old. Even my Capital Punishment argument was not without OT basis.
Jesus came to remove a heavy yoke, not to add a greater burden.
1 Corinthians 7 is the key passage to their argument.
"Now concerning the things whereof ye wrote unto me: It is good for a man not to touch a woman. Nevertheless, to avoid fornication, let every man have his own wife, and let every woman have her own husband. Let the husband render unto the wife due benevolence: and likewise also the wife unto the husband. The wife hath not power of her own body, but the husband: and likewise also the husband hath not power of his own body, but the wife. Defraud ye not one the other, except it be with consent for a time, that ye may give yourselves to fasting and prayer; and come together again, that Satan tempt you not for your incontinency."Notice how it goes both ways on your body now being owned by your spouse. No notion here of the Wife as merely property of the Husband which so many assume The Bible condones.
It is also overlooked that most of what begins this is not Paul's words, he's quoting a question he was asked "ye wrote unto me", and I'm afraid it's not easy to tell where the question stops and his response begins. And his answer to the question is not entirely a yes or a no.
But going on to verses 8 and 9.
"I say therefore to the unmarried and widows, It is good for them if they abide even as I. But if they cannot contain, let them marry: for it is better to marry than to burn."There is an insistence that the terminology here treats marriage as the only alternative to being single (which they just assume is synonymous with celibacy). And that there would be no point to this if one is simply allowed to have extra martial sex, even in a loving context with a fellow believer.
Fornication is a key word here, it's important not just to understand that it doesn't mean all Sex outside Marriage. But that it is, no matter how many times it may be used more loosely, first and foremost a word for prostitution. It's not just any random sex Paul wants them to avoid.
It is also important to know that this is a place where Paul is letting his personal opinions influence him, not enough to undermine the Divine inspiration, but it's there. "But I speak this by permission, and not of commandment." "But to the rest speak I, not the Lord". It is not the full testimony of Scripture that single-hood is preferable to marriage, in fact Jesus seemed to have the opposite opinion. God did not want Adam to be alone. The Church as the Bride of Christ is a vital Biblical doctrine.
The statement that it is better to marry then to burn with lust is not about avoiding any sexual fulfillment, you could condemn masturbation with that flawed logic, which is absurdly stupid. It's for people who need deeper intimate companionship. A need that only a committed relationship can truly fulfill. But if not fulfilled by that could lead to a certain kind of Prostitution. A kind that is not as well known today as it used to be, but you see in films and literature about older times like, The Egyptian or Baccarat and Torquise in the Rocambole novels. Where the mark winds up seeking a quasi-romantic relationship with a Courtesan. And where actual physical intimacy may not even happen.
The word "lust" is not used in this chapter, but it's always inserted by commentators. Even if it were lust can refer to more then just physical desire, in fact it can be used in contexts not sexual at all. The desire Paul is speaking of people burning with is not just the desire for physical release, it's a desire for something more.
I will also disagree with those who say this instruction is only for those "in the ministry", I do not support Organized Religion. All Believers are servants of Christ.