The first thing people say about Susan Baker is that she is very religious. "She's the kind of person," says a colleague of Treasury Secretary James Baker, "who, if you mention a problem to her, she will immediately say, 'Let's pray together about it.' "

"I'll tell you," Susan Baker says, "when my kids say, 'Mom you're such a Jesus freak,' I say, 'Honey, I have tried everything else, and Jesus is the answer.' "

It is through this faith and total commitment to helping the needy that Susan Baker has emerged as an unusual behind-the-scenes Washington player, quietly lobbying everyone from her husband to Secretary of Defense Caspar Weinberger for her causes.

During an interview at the Bakers' Foxhall Road home recently, the conversation often came back to God and the Bible. The home is bright and simple, with red and white overstuffed couches and chairs and a dining room table that shows the wear of eight children.

At 48, Susan Baker has the soft Texas voice of a young girl, and skin the color and texture of fine peach silk. She wears her blondish hair swept up. She seems at once self-effacing and secure on this day, talking about her life as political wife, mother and volunteer activist. Her conversation is sprinkled with the deferential references of a traditional wife, such as "I've lived long enough to know that if my man is happy, I'm happy . . . I'd follow him to the moon if that's where he wanted to go."

Yet, behind the mild southern exterior of a woman who has never had a career outside her home, Susan Baker has been strengthened by the tragedies in her life.

There were the hurtful years of living with her alcoholic first husband, their divorce and the predictable loss of self-esteem that comes with such a hardship. Several years after the 1969 divorce, her first husband, she says, drank himself to death at 38.

She tells this story about the collapse of her first marriage and how she found peace through God and her Roman Catholic religion:

"I got the divorce -- it was so awful and it took a long time and I thought all this time I just want to be a mother, I can be a mother. But it was awful because my self-esteem was so diminished and I was so beat down emotionally . . . All I did is sit and mope. And one night I'll never forget -- here I felt I could be a good mother -- and I found myself chasing my child all over the house, screaming and yelling, trying to hit her, trying to just physically hurt her. And something in me just snapped. It was lots of little things and that night I just came to the end of my rope. I got my kids to bed, and I just remember going into my room and shutting the door and I sobbed and sobbed and sobbed. The pain was so great and so oppressive and I said, 'Oh, God, if You are there' -- because I began to doubt if He was there -- 'if You are there You've got to help. I can't go on.'

"I just gradually began to feel a great peace -- no voices or bells -- I just knew in my heart what I had to do was study the Bible to see that God was real. At that stage, my life really begin to change. At the time, I decided to devote myself to God, I thought, dear, He's going to send me to Africa or something. But it doesn't work that way. You do what you can in your own way."

Baker was raised in Danbury, Tex., the daughter of rice farmers. It was through her husband, a wealthy Houston businessman, that she met Jim Baker and his first wife, who died in 1970, 25 years ago. The two couples were close friends and, in fact, Jim Baker is godfather to one of his stepchildren.

She lists among her closest friends here Joanne Kemp, wife of Rep. Jack Kemp (R-N.Y.), and Leilani Watt, wife of former interior secretary James Watt -- friends "I can pray and laugh with" -- and says that since she has found these "great pals," Washington has been an easier place to live.

"I just pray to God for the wisdom to decide on how to tackle each day," she says. "I went through a lot of painful years and spent a lot of time on my knees not knowing how to communicate until I learned God's words. I would kneel beside the bed and say my Our Fathers and Hail Marys before I went to sleep, with cramps in my back from kneeling, but it did not affect my life. I was saying a prayer and nothing changed. So while God was really there, I wasn't reaching Him."

Since she has been in Washington, Susan Baker says she has found different outlets for her faith. James Baker is an Episcopalian, and for a while, she says, they attended different Sunday services. Now they both attend an Episcopal church, although Susan Baker still considers herself a Catholic. She counts as her most important contribution her work as champion of the poor and homeless, and she founded a group called the Committee for Food and Shelter Inc.

When activist Mitch Snyder threatened to starve himself last fall unless the Reagan administration provided emergency shelter for the homeless, it was Susan Baker who sat by his bedside and prayed daily. She is widely credited with pushing her husband to arrange the deal between Snyder and the Reagan administration that resulted in Snyder's ending his fast, although she maintains she was a very small part of it. "I just prayed," she says today. "Jimmy knew I was sitting by Mitch's bed, and one day during all this he called from Air Force One and said, 'What would it take to get Mitch off his fast?' No one wanted Mitch to die."

Early on in the administration she persuaded Weinberger and then-health and human services secretary Richard Schweicker to expedite donations of surplus food from military commissaries to the poor. Instead of returning the food to commercial vendors, who would then give the food to the poor, the military allowed food banks to pick up the food directly at military bases. As a result of Baker's efforts, which she calls cutting the red tape, about a half-million pounds of food a year from military bases reaches the poor.

"I feel I am in a very lucky position as Jim Baker's wife to help, and to reach the people who can help," she says. "I just want to do what I can because I know it won't last forever."