The conscience is an internal alarm system that goes off according to a soul's highest perceived standard. The default standard is God's law written in the heart, but that will change, depending upon the influences upon a person. The alarm might sound for a Moslem when he misses one of his five required prayer sessions or for an Amish man when he shaves his beard, because those are their perceived standards. The prayer and beard requirements are not scriptural, but they are people's highest perceived standards, so that's what also informs their consciences.
The nature of depravity sends someone away from the law of God to his own way. Many times God's standards are lowered when someone is following his own path away from God's law. Sure, some might add to God's law, but they also will take away from it as well.
Let's say that you have a young lady wearing a pair of shorts about mid thigh, and her conscience does not sound any kind of warning to her. Why? There could be a number of reasons, but one is that her standard has changed. She is not being guided by her conscience, but by a perceived standard. If the perceived standard is wrong, and her conscience says nothing, it doesn't mean that she is doing right. Her conscience is misinformed. That's how the conscience works. It could be that it does violate her highest perceived standard, but she has already damaged her conscience. Her conscience isn't working correctly, because she has damaged it in some way, which usually occurs by not paying attention to it when it is sounding its alarm. The conscience can become almost useless to the one who has stopped listening to it.
In other words, the conscience is not our guide. The law of God is the radar that tells the warning system that the airplane is flying into a mountain, and the audible warning siren is the conscience that tells the pilots to pull up. The conscience is guided by its perceived standard. The default standard is the law of God, but that gets effected by harmful godless and worldly influences. The standard itself is the guide and the conscience reacts to the standard. The conscience never operates on its own, but always in conjunction with the information it is being sent.
Someone recently wrote these following two statements.
Can a Christian be good on someone else's nickel? Can he hitch his virtue to someone else's conscience? If Jesus wore a mustache, would an Amish man have accused him of pride?
Standards of modesty do change. How they change is worth some serious thought. And any external constraint on the life of faith, according to the Apostle Paul at least, involves a consideration of the individual conscience.
The guy who wrote this was arguing for an absence of dress standards, so that individual consciences would choose the path of goodness relating to modest dress. You can see he doesn't understand the conscience. A new Corinthian believer may have a conscience that warns him against eating meat offered unto idols, because he has a standard that tells him that's wrong. Scripture wasn't informing him that it was wrong, but it was the perceived standard he possessed about idolatry. Someone else may not have that standard, so his conscience remains silent. However, if it was wrong to eat meat offered unto idols, and your conscience was silent when you ate, that doesn't mean you should follow your conscience in that instance.
Shorts might fit a girl's standard of modesty, so when she wears them, her conscience warns of nothing. Does that mean she is right in wearing them? Is the conscience a standard of virtue? We judge, not based upon the conscience, but based upon whether it is good for the girl to wear shorts or not. If we allow conscience to guide, we are depending on mere perception, that is, subjectivity, whatever the girl thinks or feels is right. If the girl is disobeying God, if she is sinning, and her conscience doesn't warn her, are we harming her by giving her the scriptural standard? Of course not. She is being helped, because she is being given the true standard of goodness.
So what about the guy whose conscience is offended by our eating meat offered to idols? If his standard is wrong, shouldn't we tell him? Sure. We let him know. Until he knows, we don't eat. But that's because it's not wrong not to eat! We're fine not eating. And even once he knows, that doesn't mean we go ahead and eat, because it could still be a stumbling block to others. Paul writes other principles as well to guide these types of situations and decision making.
When people's consciences are being given the wrong standard, we tell those people the right standard. We inform them from scripture. If someone wears a higher standard of clothing, that will not affect the conscience of the person wearing a lower standard. Why? His or her conscience will only sound if the highest perceived standard is violated. The higher standard is not breaking her lower standard. I think you understand this.
Biblical standards are good. They give right information to a conscience. The properly operating conscience can then warn if the standard is being violated, to save a person from a moral disaster, to help him to be good.
The idea that we have no rules of modesty because we'll keep someone from using his conscience is all wrong. The guy I quoted above didn't and doesn't know what he's talking about, and he's leading people astray. A conscience is not harmed and can only be helped by being given the correct and biblical standard. Standards of modesty change in the world and in cultures. They do. They get worse. They go overboard. The Bible doesn't change though. There is objective modesty, objective goodness, even as there is objective truth and beauty. We can observe how Christians have interpreted and applied Biblical teaching of modesty through history. That's what should inform our conscience. It should be our virtue, our standard, by which our conscience will warn. If someone is immodest, we criticize and challenge. That helps someone, even if he won't believe it, and even if his conscience says otherwise.
Why would someone, like the man who wrote the quotes above, be upset about asking questions about standards of modesty? Based on what he wrote, it seems that he doesn't like standards of goodness being imposed on others. From other things I've read from him, sometime in his past, he was placed under standards on similar campuses as Maranatha. Even though they were "strict" in their dress code at the time, they also had a low standard for beauty. He reacts to the cultural deprivation with a scorched earth criticism of all fundamentalists. He attacks all the standards. We don't combat a low standard of beauty with a low standard of goodness. We should look for a biblical standard for both.