Between the battle lines. In neighborhoods of street gangs - where driveways are armed borders and folding your arms the wrong way on the street corner can be punishable by death - the struggle to bring bitter enemies together is a long, uncertain process

NIGHTFALL comes to Cabrini Green. The projects grow dark; and with the darkness, residents know, comes the threat of violent, gang-related crime. Those who do not carry weapons make their way indoors. Those who do carry them cluster in doorways, challenging any stranger as intruder and enemy.

Gordon McLean turns his small car into a cul-de-sac, as the leading edge of evening makes its way across the playgrounds; then he walks into the sprawling housing project. ``I wouldn't go into any building I didn't know,'' he says, as he goes into a building that looks like nobody knows it.

Inside, windows are blown away. Black smoke-stains curl around door frames, reminders of past fires. The walls are densely covered with gang graffiti. Mr. McLean (or ``Gordy,'' as he is known to gang members and their parents) makes his way through the cold halls. He cuts an unprepossessing figure - a street minister and social helper who doesn't look the part of your average off-the-shelf do-gooder; dark, a little burly, somewhat nervous, prone to talking in long bursts of peripatetic sentences.

``It's like a jail here,'' he says quietly. Then he knocks on a darkened door.

The woman who opens it smiles immediately on recognizing him and tells him her son is doing a lot better. ``He's been real good'' since he got out of jail, she says, obviously giving Gordy the credit.

McLean may be a figure of controversy in some circles, and his methods of reaching gang kids may be subject to question. But in this dark hallway, and in this apartment - rich with the aromas of Hispanic cooking and the noise of family life - none of that matters much. Kids get in trouble with the law here and, when they do, McLean tries to help them out. Nobody here seems inclined to forget that.

``See there,'' she says to him later, out on the street, ``all the guys love you.''

Whether it's love, or respect, or just acceptance, McLean seems to have acquired a kind of entree to the world of Chicago street gangs that few outsiders even approach. Driving around from one gang turf to another, he pulls his nondescript Volkswagen up a discreet distance from a small cluster of gang kids. Soon, a leader walks over and chats with him.

He asks about gang members. And he gets answers. ``I've been trying to explain it to myself for the longest time,'' says the Rev. Harry Roundtree, a staff chaplain at Cook County Jail, who knows McLean and works with him. ``He just has this special interest in kids.... They know when he is coming and why he is coming. He is concerned about troubled kids, and they just see the interest.''

The interest comes across as he sits in his car and riffles through pictures of gang members he has helped. ``That's what they kill each other for,'' he mutters, pointing out the trivia that can mean the difference between life and death. ``They find acceptance and family out here in the street. I contact most of the kids we know when they are in serious trouble. I get to know them pretty well. I'm the guy they can talk to. You just simply build a relationship of trust.''

IT'S been pointed out (in Chicago magazine, for instance) that gang members get more than trust from ``Gordy.'' He takes them to dinner, has them over to his nicely furnished apartment for small gatherings. Add to this the fact that these people are almost uniformly charged with crimes ranging from rapes to murders.

McLean works for the organization Youth for Christ in a combination prison and street ministry. Youth for Christ, founded in 1944, now has 220 local programs in the United States and a full-time staff of 1,900. It is interdenominational and relies on charitable donations and the sale of materials for income. McLean did this kind of work for the group for 33 years in the San Francisco/San Jose area and came to Chicago, at the organization's request, five years ago. ``Gordy likes a challenge and has a pioneering spirit,'' a Youth for Christ aide says.

The money he spends comes from a fund provided by Youth for Christ, and it's the money that raises a few eyebrows.

``Maybe these kids are just using McLean,'' David Jackson, a Chicago journalist, speculates. ``They go to his meeting of gang nations for free steaks and soda pop. They pray with him in jail because it helps to have chaplains on your side.''

But Mr. Jackson and others point out that McLean does something almost no one else in this gang-ridden city accomplishes: He gets rival gang members to sit down and get to know each other.

``He has a real impact on gang-involved kids,'' says Jack Brown, chief juvenile probation officer for Cook County. ``He is very tenacious. He changes their behavior. Kids break away from the gangs, they don't get arrested, and we don't see them down here anymore.''

McLean himself acknowledges that to accomplish this task he crosses over a line that many consider uncrossable. He hears about crimes that he doesn't report. He countenances, though he doesn't condone, behavior and attitudes that most clergymen would be compelled to condemn outright.

``If you have a son, who is doing something wrong, you don't shut him off,'' he says by way of explanation. ``Or at least you shouldn't. These guys know where I'm coming from, they know I don't condone their actions. But they know I don't condemn them as people.''

On a rainy night recently this unlikely traveler in ghetto streets - a white man with wire glasses and a heavy face, who takes frequent pulls from a bottle of Pepto-Bismol - steers his car out of a coin-laundry parking lot in the Humboldt Park section of Chicago. The streets are flanked, not by falling-down tenements, but by lower middle-class houses that show signs of decay. Poverty creeps up around the edges of everything here, a kind of crawling shabbiness. This is a part of the world where people get shot in the head for accidentally wearing the colors of a rival gang, or for folding their arms in a position used by a rival gang.

Gordy is here on business: ensuring that certain key leaders in various gangs show up for his ``United Nations meeting'' tomorrow night - a monthly gathering of rival gangs, held at his apartment and followed by a sit-down dinner at a chain steak house. At a corner, he pulls up and waits for Fireman, leader of the Vice Lords (names and gang affiliations have been changed at the request of the gang members) to saunter up to the car.

``How you doin', brother?'' McLean asks.

``Well, too many of my enemies know where I am.''

``I thought everybody liked you.''

``Well, my people do.''

Fireman knows his ``people'' the way an isolated tribal chieftain would. The bloodshed between gangs has reached such proportions that gang members hardly dare venture out of their own turf. They observe boundary lines as narrow as a driveway. Later in the evening, when he is taking one gang member back to his home, McLean has to drive a prescribed route in order to avoid crossing onto forbidden streets - and risking a bullet through the windshield.

Over the next few hours, he stops and talks to kids, occasionally picking one up and driving to a McDonald's for a chat. One such kid, Benny - quiet, bright, a whisper of black mustache above his pubescent lip; soft, black eyes showing a mingled innocence, weariness, defiance - pulls on the straw of a milkshake and says, ``I'm tryin' to give up gang-banging [the general term for gang activities, used by police, gang members, social workers]. I'm tryin' to get a job. Because the streets, man, the streets ain't about nothin'.''

LATER that night, you get an entirely different song from FreeBee, a Vice Lord. He spins out a string of crimes freshly committed and crimes contemplated. FreeBee has lots of money, as his clothes and jewelry show. Exceedingly pretty, with brilliantined black hair, he has his choice of neighborhood women. He sells drugs. And he has been in and out of jail with too much frequency to recall the specific instances. With one exception. He remembers being charged for raping a girl in a particularly brutal way; and he seems proud of it.

Finally, in the inky blackness of night, sitting outside a Cabrini project, only the outlines of his face showing, a 15-year-old member of the King Cobras tells his gang-banging stories, not with bravado, but with blood-chilling matter-of-factness.

Maybe if he had adorned his tale with heroics or machismo, it wouldn't sneak up and slap you on the side of the head the way it does. But you hear this boy talk about the murders he has witnessed and participated in, the simple savagery of his life - told with a kind of dull, unenthusiastic murmur and surprise that anyone would not understand that this was the way of the streets. And you suddenly see it all at point-blank range.

That, of course, is Gordon McLean's accustomed range of vision. He listens to these stories. He tells the kids what he thinks of what they are doing. Then, he sides with them, encourages them to get their lives together, preaches to them. ``They've got to respect God - and themselves,'' McLean says. ``Then, they can respect other people. Nobody believes in them, everybody's out to get them. People have an amazing way of living up to your expectations of them. I'm the only adult in their life who is no threat. I'm a friend with ... nothing to gain. Except that I want to see them make good.''

You have to wonder what it all accomplishes. You have to wonder, for instance, the next night, what a dozen hard-looking young men think of this guy standing in the middle of his apartment, extrapolating to them from the book of Psalms. He tells them that they need to pick their friends carefully and go their own way in life and be honorable; and it seems as if someone has just sent a butterfly in to break up a horde of hornets.

Sitting for individual interviews in the steak house that night, they talk frankly about their gang activities, about their court dates, about Gordy. To a man, they all say the same thing: that he has no ax to grind, that he wants nothing from them, that he wants to help.

Does anything change when the kids go back to the streets? ``Change is a process,'' McLean says. ``It is not a single act. It's progress when a kid who used to get picked up for assaulting people'' is taken in for a much lesser charge.

Do the gang kids themselves see any change coming out of these meetings?

Maybe. A kid gets surrounded by a rival gang. One of the guys met him at Gordy's. He tells the others to let them go. So the kid gets away without a beating - or worse. But, no mistake about this, an enemy is an enemy. And as they leave the steak house in small clusters, you can see the streets come back into their eyes. The faces get hard, the walk becomes an I-own-the-sidewalk defiance.

When a reporter goes to the back of the restaurant, he is stopped in the hall by two gang members. ``Hey, brother,'' one says quietly, ``give me five dollars.''

When the reporter refuses, nothing else is said. But it was clear that, in a different neighborhood, in a different restaurant, the conversation would have taken a different turn.

SO where does it all lead? Back onto the streets? Without much change? Only with a nice meal and a little homily?

Are they hustling this guy?

The next morning, in the hard reality of Cook County jail, with gang members packed into nearby cells, Mr. Roundtree, who works with McLean, says: ``Yeah, we get hustled.

``We call it `the con game.' And people who see it happen say, `Why waste your time with these guys?' And I say, because these same kids are going to return as men to your neighborhoods. And how you going to deal with them then?

``So I have a guy who comes in here. He tries to con me. It doesn't work. He goes and does his time upstate. Then, we get him back on the street. But we made contact. He knows us. He takes our help. He gets a job. And he calls me the other night to invite me to a party his father is throwing him because he got his high school diploma.

``Nobody has to tell me we wasted our time. Nobody has to tell me we got hustled.

``I know what we did for that kid.''