The Rev. Al Green sits back in his dressing-room chair, explaining his new calling as a Christian minister without devaluing his past work as the most successful, sensual and influential soul singer of the early '70s. Between 1971 and 1976, Green sold 30 million records, controlling the soul charts (and frequently the pop charts as well) with the romantic silkiness of songs like "I'm Still in Love With You," "Let's Stay Together" and "You Ought to Be With Me." But in 1979, Green was ordained and started his own nondenominational Full Gospel Tabernacle Church in Memphis. He has not performed or recorded pop music since then.

In his stage time here Sunday night, Green plowed old fields -- throwing long-stemmed red roses to the audience, peeling off his jacket, loosening and then discarding his tie, hop-stepping across the stage, cutting loose with the staggering falsetto outbursts that used to crop up so often in his romantic ballads. "I can't help the way I move," Green demurs. "I can't help about the message I must carry, it's just something that's assigned for me to do. I can't explain about how you reach out and touch somebody without the extension of your hand. I love roses, I give the roses and bless the people."

Green, dressed in dapper tailor-made clothes and seated in his dressing room at Constitution Hall, speaks softly but with the unconscious authority of a Sunday school teacher. He leans forward, staring straight ahead so that the meaning of his words is understood. "What I'm doing now is valuable to somebody. What I was doing before was valuable, but to a limited extent -- boy meets girl. Now we're talking about values that send judgment into eternity ."

Perhaps because of the difference between his two selves, Green often refers to himself in the third person, or the plural. "As far as we're concerned, I think our past was a good past," he says. "The songs we wrote then were given from up above.We think that our past was a good stepping stone to where we are now. It is a stepping stone, yeah!"

Like many black singers, Green came out of the church tradition; one of his biggest influences was Sam Cooke, another singer who stradled the secular-gospel fence. Green never abandoned his church raising entirely; in the midst of his secular success, he still read the Bible daily and put songs like "Jesus Is Waiting" and his classic "Take Me to the River" in his rock sets. The prevailing image, however, was of the sensual idol whose female fans once petitioned not to get married.

That idolatry came to a shattering climax in 1974, when a woman described in news reports as a "despondent girlfriend who wanted Green or nothing" poured scalding grits on the singer and then shot herself to death. The incident may have contributed to increasingly mixed concert and record reviews and a dip in sales and attendance figures; in any event, by 1975, Green had peaked.

"She [Mary Woodson] was a beautiful, gorgeous person," Green says slowly, receding into a more private place. "It was happening so fast you couldn't do anything about it anyway. That wouldn't have anything to do with my religious convictions; oddly enough, we planned the whole layout of the church before this happened."

(Last month, Green's personal demons were made public again when his wife, Shirley, filed for divorce on the grounds of "brutal beatings" and "numerous threats of bodily harm." The most recent incident, according to the complaint, occurred in March when Mrs. Green's request for money to buy milk for their baby provoked a serious beating. Green, in the midst of a multi-city tour, has not yet responded to the allegations in court. A court injunction forbids him from going near Mrs. Green until the issue is settled.)

Green, 34, dots his conversation with accents, pauses, muffled laughs and murmurs, a more quiet version of the hypnotic speech patterns and evangelical posturing delivered in performance. Off stage, he seems shy and reserved, a far cry from the peacock exuberance he displayed onstage 30 minutes earlier. The message may be different in 1981, but Green's lithe, lean body and winsome features still deliver it with the sensual familiarity of the mid-'70s, leading one woman in the audience to shout out "Al Green, you're still a star!"

By the time his acclaimed "The Belle Album" came out in 1977, Green was increasingly caught up on the artistic and emotional conflict that crystallized in one lyric: "It's you I want but it's Him that I need."

Many pop performers have had born-again experiences in the last five years, but only Green has entered an active ministry; he runs the church's affairs, preaches every Sunday, teaches Bible classes and rehearses the congregation's choir. "That's what I was called to do, see. I suppose some people are called just to evangelize, but I was called to do something else . . . It's going to be good, it's going to be interesting , I tell you that. I want to do gospel, but I'm going to do some gospel you ain't never heard." Green says that his next album is going to be "a lot hotter , because the spirit is there."

Like Bob Dylan, Green has had to suffer speculation about his ongoing commitment, particularly in light of his legal problems and the impact of gospel's economic reality on a man who once got $40,000 a night and could sell out the Capital Centre.

On Sunday, Constitution Hall was less than half full. Green's records no longer sell in the millions (though his latest, "The Lord Will Make a Way," has been No. 1 on the gospel charts for 12 weeks).

"You cannot rely upon people to make up your personality," Green shrugs. "If God changed you, He changed you; if He didn't, He didn't. Whether people know or don't know, hey! All I know is whereas I was blind . . ." Green pauses, knowing the phrase can be completed in silence.

Last year, the Rev. Al Green stopped giving concerts entirely, splitting his time between his church and his 21-room mansion 40 miles away. "I put on my winter jacket and go walking out among the cows at the farm. I walk along the hillsides and throw rocks in the river and think about it," Green says, as if he's back in the mountains outside of Memphis instead of a dressing room. "My life is like a book, like something you see on television . . . and it's unbelievable because all of the scenes have been played out, all of them have been done before. But there's nothing I can do about it because life goes on.

"I came by appointment from one high to do a job, to do a work. My body language on stage may be the same, but the Lord knows who I am, He knows who He called, He knows who He appointed. It's the only reason I'm here. He didn't say 'I want you to stop singing rock and roll and tell the world that I live.' It's just the work we're doing now is of a higher caliber."