Q. Can you tell me how the Bible defines sex? Isn't it true that society then regarded sex as being full penetration?
The Bible does not have an equivalent word for 'sex'. Physical intimacy and sex are therefore synonymous. The nearest would be the Hebrew word yada which means to 'know' and is used euphamistically of sexual intercourse that leads to pregnancy, i.e. sexual penetration with ejaculation and fertilisation (e.g. Genesis 4:10). The Song of Solomon, which is an ode to sexual love, takes this further by including the minutae of foreplay displayed in poetic and metaphorical language. And Christ takes sex to its most full and comprehensive expression by including the thoughts we have about it (Matthew 5:28). Sex, then, in the biblical sense, is the intimate union between a man and wife (or wives) that involves the thoughts, emotions, and physical senses that in turn lead to full coitus and (if fertilisation takes place following ejaculation) conception. Sex, then, is the desire for physical intimacy of any sort that leads ultimately to full union.
Some pagan societies in biblical times had a very narrow view of what sex was and considered it to involve only penetration of one partner by the other. Under this definition, what two women in a polygamous (or even unmarried) relationship did physically would not have been considered as sex. This is not, however, the biblical view, which is that sex is the intimate "knowing" (yada) that comes from any form of physical contact that would lead to full coitus, even if it does not reach that point. Accordingly in biblical times a man couldn't even touch a woman who was either not his wife or not a member of his immediate family (e.g. mother or sister). Any idea that physical contact that does not involve full coitus (penetration) is not "sex" is entirely unbiblical.
People often ask me, in light of this, how our conduct should be between the sexes. Should members of the opposite sex not married to each other even shake hands or hug? I personally favour traditions that do not encourage this such as the Indian, Chinese and Japanese customs of bowing and the European customs of curtseying, bowing and clicking heels. It has been pointed out, though, that in the New Testament Church (Messianic Community) that the saints kissed one another on the mouth with a holy kiss, and it is true that this custom did arise. It was, however, disbanded in the post-apostolic era because of its sexual abuse. (Others claim that is was no more than cheek-kissing though this would not necessarily explain the later abuses). As a result, most Christian commentators would agree that whatever in modern cultures is symbolic of the deep affection Christians ought to feel toward each other - a kiss on the cheek, a warm handshake, a grasping of both hands, etc. - is the equivalent of the apostolic command:
The key word is 'holy' (set-apart) and I have no doubt a time will come when more intimate hugging and kissing will be normative in the Millennial Kingdom. In the meantime, with ever worsening promiscuousness, we advocate in our Order that the non-contact traditions be employed outside the local fellowship as a general rule with exceptions made between families who know and trust each other with the permission of the husbands. This way, I feel, a proper balance is maintained and the biblical standards are maintained. What we do not want to do is create distance between believers whose relationship is already spiritually intimate by virtue of the Cross.
"Mutual salutations, as they express love, so they increase and strengthen love, and endear Christians one to another: therefore Paul here encourages the use of them, and only directs that they may be holy - a chaste kiss, in opposition to that which is wanton and lascivious; a sincere kiss, in opposition to that which is treacherous and dissembling, as Judas's, when he betrayed Christ with a kiss. He adds, in the close, a general salutation to them all, in the name of the churches of Christ (v.16): 'The churches of Christ salute you; that is, the churches which I am with, and which I am accustomed to visit personally, as knit together in the bonds of the common Christianity, desire me to testify their affection to you and good wishes for you.' This is one way of maintaining the communion of saints" (from Matthew Henry's Commentary on the Whole Bible on Romans 16:16: New Modern Edition, Electronic Database. Copyright © 1991 by Hendrickson Publishers, Inc.)
"This mode of salutation has been practiced at all times; and particularly in eastern nations. It was even practiced by 'men'; see the note at Luke 22:47-48. The use of the word 'holy' here serves to denote that Paul intended it as an expression of 'Christian' affection; and to guard against all improper familiarity and scandal. It was common, according to Justin Martyr (Apology), for the early Christians to practice it in their religious assemblies"
(from Barnes' Notes, Electronic Database. Copyright (c) 1997 by Biblesoft).