Long hair was not widely considered feminine at that time nor a sign of homosexuality in males. In fact homosexuality was acceptable in ancient Rome with their short hair for the same reason it was acceptable in previous societies that were military conquerors. They were not well civilized and it was their being not well civilized that made them conquerors. What typically happened to the really uncivilized, but for the time apparently "great" societies, like that is they eventually did become civilized themselves only to have the uncivilized people on the borders manage enough organization to conquer them in turn. So the center of "civilization" moved from Sumer to Babylon to Persia to Greece to Rome. At first Egypt was isolated enough not to be taken in the fold but not later. Rome is at the end of the cycle though. It wasn't "conquered" so much as it just fell apart in becoming ever so gradually more civilized. After that, the notion of one world goverment was mostly abandoned.
Many modern day people mistake the Roman "crewcut" for a "Jewish" haircut. The Jews rather had what was for those times and those neighborhoods at least a rather long tradition of advanced civilization and did not wear crewcuts and even later Jewish communities typically had long hair on males. The crewcut did become part of Christian culture though and you can see that in the book of Revelation with the notion of "women's" hair.
Of course there was and still is much confusion what most of these things mean. One thing that became considerably well established was that the crewcut was better for the military as it was an advantage in combat. That is practically speaking only. Symbolism is another thing. You have people thinking the "military" is more "manly" so a military crewcut is also. And you also have people complaining that Rome was homosexual and so was their military with its crewcuts.
Although we often see Christ portrayed in art with long hair, since that is how Jews wore their hair, the crewcut was more the sign of Christianity later as it pulled away from the Jews, especially with the Christian military. It might well have been Christ wore a short haircut himself.
However Christian the crewcut was, after Rome fell it did not have the dominance in society it had before. And it would not dominate again until World War I. With World War II it revived somewhat the long lost notion that the crewcut was a "Jewish" hairstyle perhaps because of the anti-Semitism of the Nazis.
Televison, arriving just after, further pressed the notion that short hair on males was the norm.
Some Americans began taking most of their knowledge of the world from television. Others read more. Some Americans did not consider war the necessity others did. There was some of the same confusion that occured with ancient Rome.
By the time of the Vietnam Conflict a very clear and widespread opposition to war was evident in American society. It had opposition in all walks of life and income levels. And many "knew" that long hair was not a "military" thing. The military propaganda of the time was that long hair meant something else entirely; irresponsibility, loose behavior and so forth.
Quite many people at the time knew the propaganda for what it was though, and the military involvement in Vietnam was ended. Communism was defeated later even with the military in that considerably reduced role.
Without having a war to protest many American males saw no point to wearing long hair and copied styles from television, which mindlessly continued the military propaganda.
America today is much like ancient Rome; militaristic, homosexual, siezing wealth and giving it to a large standing army, wearing crewcuts, and essentially atheist despite a few long dead and meaningless religious rituals.
A few maintain a delusion that they are living godly lives by their crewcuts alone. Remember how crewcuts saved the Jews from Hitler? Of course they are not well educated. Their television is awash with casual attitudes about sex generally and homosexuality, but that's fine for them since they have crewcuts and support their military.
Not believing in God, they all, Republicans and Democrats, do believe in the military. The Democrats believe the military will enable people to do whatever they want, much like the Roman generals gave money and land to the uncivilized masses. The Republicans believe the military will prevent people from doing whatever they want. You can read more about that in the article on cultural inversion.
The reality is that most Americans and their military are fighting against God. All the current problems are the result of that. They consider themselves "scientists" despite a glaring ignorance of it, have a blind faith in medical treatments that don't work, coerce payments from all citizens for those treatments, which is "establishing" a "religion" really, that is a faith in medicine rather than God, but still a religion. And the only things appearing in their debates are tax and spending levels.
Long hair on males is supposed to mean you don't believe in war and live by godly rules, what it unfortuitously means today in America is lost in the shuffle.
Among concerns about long hair and facial hair is how much that might interfere with good police work. Probably most people in America believe the "Christian" clean shaven style is most beneficial to police work since it often seems that style makes people easier to identify. That probably isn't entirely true. The difficulty usually found in making an identification is largely the result of too brief an encounter, not hair style.
This has been demonstrated time and again in my long career. Suppose there are two delivery men, one delivers vegetables and one delivers paper cups, to a restaurant. Suppose they are very roughly the same height, weight and general appearance. Even though they might have the same "Christian" hair style they are often mistaken for one another. The reason is the staff at the restaurant changes.  Many restaurant employees are still in school and there is a high turnover rate in the employee roster. The long time employees of the restaurant will more readily identify the delivery men, especially if they deal directly with them.
People who find they are often mistaken for each other that way sometimes agree to alter something, have one wear a mustache or slightly longer sideburns for example, to avoid confusion.
Brothers Jerry and Terry Kilgore, well known in Virginia politics, avoid confusion by Terry wearing a moustache. Both have Facebook accounts and you can see the difference. They are identical twins, by the way.
A very full beard is often considered hiding too many identifying features of a face, but beards come in as many different sizes and shapes as faces do, and really more different colors as well. People who don't see many movies might mix up Al Pacino and Dustin Hoffman despite the fact that they are really very different in appearance. Remember the problem at the restaurant. People who have seen several Al Pacino movies will readily recognize him even if he has a rather heavy beard as in the movie, 88 Minutes.
The use of fake beards is a potential problem, but making one that looks real isn't so easy as it might seem in the movie industry. In the movie, The Prestige, a fake beard is used rather successfully to fool the other characters in the movie and the audience as well. The audience is fooled by too quick and too far camera shots and exceptional quality makeup.
The main reason men don't wear beards might have more to do with beards being mightily uncomfortable.
Among the reasons license plates are required on automobiles is that making identification can be difficult with very brief encounters.
Quite many of you will be surprised to learn this, but the Christian crewcut is more about conformity than about making differences easier to recognize. As an example consider the "part" men put in their hair. It is usually on the right. When I was young I parted mine on the the left and there were complaints that it wasn't the "correct" way. Notice Virginia Governor Bob McDonnell parts his hair on the left. Did you notice that before? You probably would have in times gone by. These days parts are generally "middle-right."
The apparent tendency of most people is to try to appear the same. They try to wear the same clothes and hairstyles. It really isn't the identifiability that matters for them, it's the conformity. The "middle-right" part actually makes men look more the same, including people who might have difficulty getting any "part" to hold at all. Making it all the same is what it has always been about for most Christians.
Whatever your complaints about Christians, and there have been some bad ones in history, there is that outreach to the wide world, to bring them into the fold, to make all the same.
Some of the more recent broadcasts that prove the point about identifying people with beards include; an episode of The Big Bang Theory where the ensemble cast males play a team returning with full beards from a long scientific expedition, and a sketch on Saturday Night Live where the ensemble cast plays Greek gods, several males with full beards. On each program the cast was readily identifiable by anyone with even a passing familiarity with the programs and their casts. The tricky one on SNL was a member of the band featured that week shown only in a far shot.
Of course there are countless examples over the years in television and movies of easily identifiable people with beards. I usually don't mention Ernest Borgnine or Donald Sutherland in these debates because they have rather distinctive features and the claim is made that those features only make the identification possible. Al Pacino, however has a face much like thousands, not meaning any slight here to any of these actors.
It only makes sense when you consider how many centuries the "Christian" crewcut was not the dominant style in the world. You might have difficulty distinguishing the Jews at the Wailing Wall, for example, but they've been distinguishing each other for countless generations. How did they do that? By magic?
There is a rule in many circles that neither men nor women should wear their hair past their eyebrows. It should be combed, tied, otherwise styled or perhaps cut at least about an inch from the eyebrows. That is a probably a good rule for many reasons whatever help it might be identifying anyone or not.
The veils that disguise everything but the eyes, worn only very rarely by Muslim women in public, are not part of any longstanding religious tradition. A considerable amount of veiling has been though.
Of course with very young children it can be difficult to distinguish boys from girls. The reason people for centuries never guessed that would be a problem is that they didn't allow children that young in public without parental supervision or in the supervision of people qualified, informed and delegated to act as parents. Since guardians knew children by name and parentage there was no question to even consider. There is of course the famous Bible story of Jesus "teaching" in the temple at age twelve without his parents' knowledge or consent. When the Bible says that he was "subject" to his parents for that it is generally taken to mean that he was reprimanded and perhaps punished.
Much later with so called "public" elementary schools there is what might be considered better preparation of children for their eventual public life. It should be noted though that the situation isn't truly public. In reality it is the same as in times past when qualified, informed and delegated people acted in place of parents.
Children who for whatever reason might be more public than usual such as the Charles Dickens fictional character "Tiny Tim" might have boys' hair cut at the shoulder, which might help denote a male without being a military style at all.
It is important to understand that however anyone's hair is styled it shouldn't have anything to do with appropriate gender roles. Jewish boys probably played games of "war" and Jewish girls probably played games of "house" like any other children from time immemorial. Appropriate opposition to war would be learned as they grew.
Henri Estienne