AT ONE TIME of her life, Justine Merritt wanted only to be "the perfect wife and mother." Now, at 61, she is literally trying to needle the mighty of the United States to stop the arms race and rid the world of nuclear weapons.

Justine Merritt is the founder and moving spirit of the Ribbon, a unique anti-nuclear protest, which will be unfurled in Washington today. It is a collection of 25,000 pieces of cloth, each 18 inches by 36 inches and variously embroidered, netted, appliqued, quilted, painted, batiked or woven, which will be wrapped around the Pentagon, the Lincoln Memorial and the Capitol. Ten thousand women are coming by bus, private car or charter plane to tie the 15-mile ribbon around the seats of power -- "a gentle reminder of the world we care about."

"It's to say to the government that we love babies and butterflies and Mozart, and that all those things would be destroyed in a nuclear war."

Justine Merritt is no artsy-craftsy, dithering grandmother. She is a vital, humorous, buoyant woman, who has lived and suffered a lot and has seen the underside of life. But when she talks about hope, her dark eyes shine and she believes that all those women, taking all those stitches, have sewn out their fear in depicting "what I cannot bear to think of as lost forever in a nuclear war." Doing that, she avers, has given them the energy needed to turn their leaders around.

When she first heard about the Hiroshima bomb, Justine Merritt, newly grduated from Northwestern University and working in New York, rejoiced. It meant the war was over, that she could marry her high school sweetheart, who was then in naval training. She and her husband settled in Harvey, Ill., and she had five beautiful children, joined the PTA and "baked marvelous cakes." In 1946, she read John Hersey's searing account of Hiroshima on Aug. 6. She tuned out the mushroom cloud.

She generally voted Democratic, but spurned politics, even the League of Women Voters because "I didn't want to be controversial." When her children were old enough, she became a high school English teacher.

The killing of the Black Panthers by Chicago police in December 1969 changed her life. "I wondered about the good Germans during the Nazi Reich. I was living in a world where you can murder two black kids in their beds and life goes on."

She quit her job, ended her "lousy" marriage, went to work for an anti- racist organization and settled in a commune "with a bunch of radical Unitarians." In time, she took a job at Unity High, an all-girl black Catholic school on the South Side of Chicago. She taught and counseled girls from large families who encompassed the range of ghetto traumas: "one brother a pimp, the other an alcoholic and she pregnant."

In March 1975, she sat down to write an indictment of Christianity. By page 38, she had lost the argument, and "spiraled back to the traditional Christianity of my childhood."

She decided to start over in Denver, writing and "living happily ever after." She was so poor, she qualified for CETA, and became supervisor of a group home for adolescent males in trouble with the law. She soon quit.

"I would make chocolate chip cookies and we would sit around and talk about things and then he would go out and kill somebody," she remembers ruefully.

She was still blotting out her nuclear fears. But in 1980, she turned and faced them. At an Ignatian retreat -- she had been converted to Catholicism five years before -- she prayed that God would send her to South America as a missionary. "All my friends were in the peace movement, and I was running away. I chose South America because I once heard Edward Teller say that there will always be a South America, and if I went there as an aging missionary, they wouldn't say I was a commie, and I would be safe."

But she didn't go, and two years later, having written a poem called "Gift," the idea of the Ribbon came to her. Let women take the time to stitch out their dearest treasures in life on beautiful banners. Get enough to tie a ribbon around the Pentagon on the 40th anniversary of Hiroshima. It struck her as infinitely more rational than making more weapons.

Justine Merritt floated the idea in a flyer to her Christmas card list. The Sisters of Loreto signed on. Stitchery magazine wrote up the the largest piecework project ever envisioned, and the needlwomen of the country responded. The Ribbon's mailing list grew to 10,000. The Arlington Center for New Creation, an ecumenical church group took on the logistics of Ribbon Sunday. Justine Merritt appeared in Vogue, People, Mother Jones and Ms. magazine, was interviewed on British, Japanese and American television.

She is often asked these days what she would say to Ronald Reagan, the advocate of peace through strength.

"I would like to talk to him in Santa Barbara, leaning on the fence of his ranch. I would just ask him, 'Where would the horses be?'