The Rev. George W. Webber, a Protestant minister and educator whose quest to make religion more socially relevant led him to remake a major seminary, start storefront churches in East Harlem and begin a program to educate prison inmates as pastors, died Saturday at his home in Maplewood, N.J. He was 90.

The cause was complications of Alzheimer's disease, said his wife, Helen.

Mr. Webber, known as Bill, abandoned his plans to become a lawyer during lonely night watches as a gunnery officer in the Navy during World War II, his wife said. Instead, he decided to become a minister, even though his wife said that he was not previously pious.

Mr. Webber's motivation, she said, was "to make things better in the world, to make them right."

He went on to join a generation of activist clergymen that included William Sloane Coffin Jr., and ministered to the poor, protested war and, in general, put themselves at the center of the searing issues of the time. When Yale presented him an honorary doctorate in 1981, it called him a "prophet for the cause of justice."

Mr. Webber's saw his mission of elevating the urban disadvantaged as a way of strengthening mainline Protestantism at a time when many Protestants were migrating to the suburbs. Though other Protestant leaders shared such views, Mr. Webber's actions were bold -- beginning with moving his young family into a low-income housing project in Harlem.

"Bill went further," Dale T. Irvin, president of New York Theological Seminary, said in an interview. "He knew it was going to take a transformation at the very root of what it was to be Protestant."

Mr. Webber's most public role may have been as president of the New York Theological Seminary, a post he held from 1969 to 1983. Beyond restoring a financially tottering institution and doubling enrollment, he recast the traditional missionary school into a training ground for black, Hispanic and female clergy members dedicated to helping "the forgotten." A successful method was admitting students without college degrees to do graduate work.

"Generations of students and faculties and ministers have followed his model," Serene Jones, president of Union Theological Seminary, said Monday in an interview.

An enduring initiative has been a program for inmates in New York State at the Sing Sing Correctional Facility to earn master's degrees in theology. Around 350 men have so far graduated, and many have gone on to careers in churches and social service. Recidivism has been low.

One of 14 men who graduated in 1993, Randel Glover, said at the ceremony, "I've come from so very low, and this is very high for me."

Jose L. Reyes said, "I no longer consider myself the island that I was."

George William Webber was born in Des Moines on May 2, 1920, to a father who was director of the local Y.M.C.A. and a mother who had a weekly radio show reviewing books. He graduated from Harvard magna cum laude with a history major before joining the Navy in 1942.

After the war, Mr. Webber earned a bachelor of divinity degree from Union and a Ph.D. in philosophy of religion from Columbia University. (He rejected the honorific "Dr.," threatening to give a failing grade students who used it.)

Mr. Webber became dean of students at Union, and in 1948, founded the East Harlem Protestant Parish in 1948, with two other recent seminary graduates, Don Benedict and Archie Hargraves. The result was the string of storefront churches.

Mr. Irvin said the three drew inspiration from reading the Bible, in an allegorical, not fundamentalist approach. They hoped to make their storefronts forces for change. Mr. Webber used his pulpit to thunder home the point: in a 1950 sermon he asserted that people living in East Harlem were "treated not as persons but as things" by the police, school officials and landlords.

He described his experience in urban ministry in three books: "God's Colony in Man's World," "Congregation in Mission" and "Today's Church."

Mr. Webber is survived by his wife of 67 years, the former Helen Barton; his sons John, Tom and Andrew; his daughters Katy Webber and Peggy Scott; 11 grandchildren; and three great-grandchildren.

Over the years, Mr. Webber protested the Vietnam War and other American policies and was arrested several times. In 1974, these activities provoked the United States ambassador to Vietnam, Graham A. Martin, to write a four-page letter to Mr. Webber after Mr. Webber led a group of antiwar activists to Vietnam.

Mr. Martin sent pictures of children killed and maimed by rocket attacks from Communist forces. He suggested that they could have been saved if Mr. Webber had heeded the ambassador's request to intercede with the Vietcong, implying they were his friends.

Mr. Webber replied that he had no influence with the enemy, and that he was shocked by the ambassador's statement.