A tale of two brothers, this -- Marvin and Carvin. If you have difficulty keeping their names straight, chances are you won't have better luck with their faces. They're twins, all right, 29 years old, two of the four brothers (Michael and Ronald are the others) who make up the Winans, the hot contemporary gospel group that performs tonight at Constitution Hall.

Right now they're savoring the sweetest irony of their career: "Ain't No Need to Worry," their hit single that features Anita Baker, is getting airplay on radio stations that generally play only secular (and often steamy) pop music. With its sensuous, funky back-beat and shimmering production, the ballad fits right into contemporary formats. But the chorus has a distinctly religious twist: "Makes no difference how dark the night/ If you trust in God it's gonna be alright/ You just wait a little while/ (It'll be all over in the morning).

Mention the song's success and laughter rumbles out of Marvin, as if he's just seen God tinkering in those mysterious ways of his. "The irony," he says, "is that we were all brought up in a strict sanctified Pentecostal home, where we didn't play or even have R&B music, and to end up on the R&B charts -- the last time I looked we were at 18 with a bullet -- well, it just goes to show that the message of God is universal."

"They're calling us R&B or pop gospel or whatever," counters Carvin in a voice several shades lighter. "But it doesn't matter. We know what we are. We sing positive songs that have a message. We try to do it tastefully -- we don't want to chase people away. Maybe the funky beat gets them first, but then the message about the Lord Jesus sinks in."

Even today, you won't find an R&B album in Marvin's home. Better not ask Carvin, though. He admits to having somewhat more liberal tastes, and probably has at least a few around. Then again, if really pressed, even Marvin would probably 'fess up to bringing home one pop album recently: Michael Jackson's "Bad." The Winans, after all, performed with Jackson on the song "Man in the Mirror." But for the most part Marvin doesn't listen to pop music. Never has.

There was a time, though, when he could hardly escape it. The Winans children -- 10 strong -- grew up in Detroit in the '60s, when Motown was a hit factory. Stevie Wonder lived a block away, the Four Tops not much farther. On the way to school the Winans would pass Motown mogul Berry Gordy's house. Among their classmates were the Spinners' kids.

"So we were nestled in this Motown environ," Marvin says, "but we simply" -- and here he pauses, warning that it may sound corny to some -- "we simply accepted the Lord Jesus as our personal savior and that sealed it. It wasn't because our parents wanted us to sing gospel music, it was because we wanted to."

To hear Carvin tell it, some of the Winans wanted to sing gospel more than others. He, for one, hated the gospel quartet music he had to listen to and sing as a kid. Still does, for that matter. Finds it depressing and "draggy."

"I thought our parents were very strict with us," Carvin says. "There were all kinds of things we couldn't do, and there were times, I guess, when I resented it. Now I look back on it and see how much good it did us, but I really didn't like that quartet music. I always liked a more contemporary sound."

Not Marvin. While his brother was attracted to the music of Andrae Crouch and other progressive gospel artists, Marvin could always find enjoyment in the sound of old-fashioned groups like the Swan Silvertones, the Nightingales and the Violinaires. As long as it was written and sung well, he liked it.

The brothers' differing tastes are now reflected in the music they write for the Winans. "I think there is a clear-cut difference," says Marvin, who writes most of the songs. "Carvin has more of an R&B sound. We used to call him 'Alley Man,' because he'd like that alley music -- that gutbucket sound. Of course, after I wrote 'Very Real Way' -- a song with a churning rhythm track -- he turned to me and said, 'Now who's writing R&B?' "

A couple of years ago Quincy Jones signed the Winans to his Qwest label, an association that later led to the group working with Jackson. But Jones would be the last person to take credit for their success. In fact, the Winans didn't even meet him until they went to the Grammy ceremonies to pick up an award for their first album, "Let My People Go." Clutching the award, Marvin introduced himself by saying, "Hi, Quincy. Thanks."

As Carvin sees it, the group's strength -- and the strength of its new album, "Decisions" -- lies in its harmonies, its tight sibling blend. "When we work on a song," he says, "the parts just seem to fall into place. We just know each other so well that it just comes naturally."

Not surprisingly, Marvin offers another opinion -- that the harmonies take a back seat to the songs. "There's a scripture that there's no temptation that is taking you but such that is common to man," he says. "So my quest is to take these experiences that are common to all of us and find God in them ... When you hear our songs, you know we've lived them."

The quartet's music hasn't changed much over the years -- several of its recent recordings were actually written by Marvin when he was a teen-ager -- and neither has its audience. The Winans have been touring since 1975, singing to both the "churched and the unchurched," as Marvin puts it.

Two summers ago the group was invited to play at Concerts by the Sea in Redondo Beach, Calif. A nice amphitheater on the Pacific coast, they surmised. Turns out they were half right. It was by the Pacific, Marvin says, laughing, but it was no amphitheater. It was a bar.

"I said, 'Oh my God, what's the church community going to say about this?' Well, we went in and there were all these 60- and 70-year-old churchwomen in the audience -- with their hats on. I tell you, we had the best time.