(The following is condensed from a conference talk I gave on this topic two years ago.)
Feminine modesty is a difficult thing to define. If we try to define it by directly addressing such things as skirt length or necklines, we will quickly lapse into pietistic pronunciations that cannot be supported by Scripture. As Christians we would not claim that morality changes as cultures and situations change, yet we must acknowledge that what seems to be properly modest attire in one situation (say, for example, at beach picnic), would be immodest in another situation.
I asked an American Christian woman who lives in an Islamic country whether she wore the same sort of covering the Islamic women wear. She said she did. She told me that if she did not, she would communicate to the local women that Christian women are wicked. She wore the covering so that Christ might not be blasphemed. I think that gets to the heart of the matter. What we wear and how we carry ourselves are forms of communication. We need to concern ourselves with the message we are sending. Based on those considerations, I developed the following definition of modesty because I think it helps us to keep a correct focus as we evaluate our clothing and our behavior.
Modesty is that quality which flows from a humble, reverent, and chaste mind and heart, and manifests itself in speech, behavior, and dress that communicates a moderate estimation of one's own worth and importance, and a high estimation of the beauty of purity in Christian marriage.
Before we do a hemline check, then, we need to do a heart check. There is nothing wrong with wanting to look good, but there is something wrong with wanting to look flirty. Being flirty says, "I value licentiousness over purity." There is also something wrong with wanting to be the center of attention. The message we are communicating ought not be, "Hey, look at me!" We need to act and dress in ways that are appropriate to the situations in which we find ourselves.
Another aspect of communication is miscommunication. We often send messages we do not intend to send. This is especially true with women and men.
Men are far more visually-oriented than women and women are not naturally aware of the difference. To be more blunt, men can be aroused and tempted by sight in a way we women just can't relate to. (Women's sex magazines are not the big market men's magazines are, are they?) Women, especially young women, can be completely naive to this, and would be absolutely shocked to know what is going on in the minds of men--even good respectable men--who see them dressed in a revealing way. What seems to be friendly innocent fun to a young lady can seem like a come on to a young man. If you don't believe me, ladies, ask your husbands or fathers. Parents, tell your daughters what they cannot otherwise know and warn your sons about naive young ladies. Daughters, take your parents' counsel cheerfully when they ask you not to do or wear a certain thing. Remember your naivete and trust their experience and their love for you.
Our immediate reaction might be, "Well if he's got his mind in the sewer, that's his problem, not mine." Fair enough, but are we not brothers and sisters in Christ? Shouldn't we consider the weaknesses of others and help them not to sin rather than tempt them beyond what they can bear? Just as women are warned constantly in Scripture about gossiping, men are warned constantly about lust. It is a weakness of the flesh that we do not want to encourage. Weakness in this area has brought many a good man down, removed men from pulpits and destroyed families. In the interest of the holiness and purity of the church, in the interest of respect for the leaders of our homes and churches, in the interest of the good name of Jesus Christ, let us communicate a high regard for the beauty of purity in marriage.
Unmarried women who would like to be married sometimes use flirtatious behavior as a way to attract a man. Is this wise? Flirting communicates, "I am available to you." If a man desires a faithful, godly wife, will he choose a woman who says, "I am available to you," to men with whom she has no commitment? Will he expect her to change after they are married? An unmarried women would be wise to show a man she wishes to attract how highly she will esteem her marriage vows.
With all that principle out of the way, we still haven't discussed the rules for dressing modestly. That's mostly because there are no hard, fast rules. But there are some suggestions I will pass on as advice to help us consider what it is we are communicating and whether or not we are becoming a temptation to our brothers.
Revealing anything from shoulders to mid-thighs beyond a non-revealing neckline can be provocative in most situations. Bare shoulders can be okay in formal wear, but be careful.
Clothing position changes when your position changes. Check out how that skirt looks when you sit down, or that blouse when you reach or bend over.
Clothing that is too tight is almost as bad as leaving parts bare. (That goes for tops, pants and skirts.) Growing and developing girls or ladies who tend to lose and gain weight need to check to see if what was modest yesterday might be provocative today.
Transparency in clothing can also be a problem. Wear the necessary undergarments to hide pantie lines, bra lace, and body details such as nipples and navels.
We must take our figure types into consideration, as well. Some figures are, well, more womanly, shall we say, than others. A certain cut of dress may be very provocative on a buxom woman, yet perfectly acceptable when worn by someone with a petite figure. Not fair? Well, who ever said life was fair?
Parents need to be careful how they dress young daughters. Often the clothing sold for young girls (toddlers) would look trashy on a young woman. If you teach your four-year-old to wear skin-tight stretch shorts and a tube top, she will expect to be able dress the same way when she is sixteen. It sure would be easier to teach modesty from an early age than to try to impose a different standard later on.
Lest we become too prudish about modesty, let us remember that women are told to adorn themselves with modesty, but they are not told not to adorn themselves. (1 Tim 2:9) Even the Proverbs 31 wife is described as being adorned in purple and scarlet. As in many things, we must walk that line between legalism or pietism on the one hand and licentiousness on the other. I think the best way to do that in regards to modesty is to ask the question, "What am I communicating?" and if we are to err, err on the side of caution.