The Real Issue in Modesty
I see a variety of discussions about modesty. Often they seem to devolve into disputes about issues like women's empowerment, men's lustful habits, and where exactly the lines on the body should be. I have no interest in starting another such dispute, so let's not go there. What I do want to do, however, is make a couple of other points that need more attention.
We might note that the term "modest," with respect to clothing, has more to do with wearing too much than with wearing too little (see I Timothy 2:9 and I Peter 3:3). Too little clothing would be considered nakedness, and this, of course, depends upon the circumstances (private, public, married, etc.). Do we care about that? And no, I don't think there is a different standard for men than there is for women. But enough on that for now.
There is something else needing stressed. I'll set this one up this way: we usually see discussions of modesty surround the question of whether something is going to make other people lust or think inappropriately (usually men because they are … men). Surely if we know that someone has a problem, then any Christian who loves his or her brothers and sisters in Christ will be willing to forego even what they defend as a liberty in order to help another who struggles. That's basic Romans 14 stuff.
However, the motivation given in the passages regarding modesty does not address doing it for the sake of others. After Peter pointed out that the external clothing is not where it's at, he said that the focus needs to be "the hidden person of the heart with the imperishable beauty of a gentle and quiet spirit, which in God's sight is very precious" (I Peter 4:4). When Paul gave the instructions in I Timothy 2:9-10, he said the dress needs to be what is proper for those who "profess godliness."
These are speaking about the inner person, and the point both Paul and Peter are making is that the outer is going to reflect the inner (cf. Matthew 15:19). This means that modesty is self-regulated because it begins in one's heart. Just know that what you wear will reflect what's on the inside, and this matters to God because you are His. "You shall be holy, for I am holy" (I Peter 1:16).
The primary reason we ought to dress appropriately is because God finds a particular attitude precious (of great value), and our dress will reflect this attitude. What others think or don't think is not the issue raised by either Peter or Paul. What God thinks is primary. An attitude that seeks the character of God and doing what is precious in God's sight is what this is all about. The question then is how we want to represent what God considers to be of such great value. Modest dress shows a modest heart.
Put this in perspective. Nothing is hidden from God. Everything is open and laid bare to His eyes (Hebrews 4:13). There is no part of ourselves that we can hide from Him; it's not like His eyes need to be shielded from anything. Even so, there are appropriate ways of dressing and acting based on this attitude that God finds precious. The goal in dress is not to impress others. Nor is it even to try to control the way others may think in their own hearts. The goal is to manifest the character of God, to do what He finds precious, and so to glorify Him.
The next time we wonder about whether our clothing is appropriate, instead of wondering, "Will a man lust?" or "Will a woman think something inappropriate?" ask first, "Will God find my attitude precious and my dress reflecting this attitude? Will this glorify Him?" That will put matters in proper perspective.
Once God is taken from the equation, the rest really does not matter. If we want to ignore what God finds precious, then we'll do what we want anyway. A man who is given to lust will lust regardless of what a woman wears (and vice-versa). But when we dress in a way that reflects a heart seeking after God's heart, we've done well no matter what others may think.
Someone may wonder, "but none of this answers the question of what specifically we can or cannot wear, or where that line is between modest and immodest." Neither do those texts in I Timothy 2 and I Peter 3. We are expected to learn something of God's character then act accordingly in humility and wisdom. Or we can be proud and selfish. That's on us.
Agree or disagree, but if we have to debate the exact line in inches on someone's legs or torso, then I have to wonder if we are asking the right questions. Regulate yourself with a heart for God. When you get dressed, think of your motivation. Know that your body belongs to God first (I Corinthians 6:19-20), then to your spouse (cf. I Corinthians 7:3-4). Ask, "Does this reflect an inner attitude that God finds precious? Is this proper for professing godliness?" Be honest. You'll likely know the answer and what to do next.