In a story in yesterday's editions, the man who will serve as Cardinal William Baum's secretary at the Vatican was incorrectly reported. Msgr. James G. Gillen will accompany Baum. Msgr. W. Louis Quinn will remain as pastor of St. Matthew's Cathedral.

Cardinal William W. Baum said a low-key farewell to Washington-area Catholics yesterday in a mass at St. Matthew's cathedral. He will leave next Sunday for Rome for a new post that will make him the highest-ranking American at the Vatican.

"With the sign of the cross of Jesus Christ my life with you began almost seven years ago," the cardinal began his homily at the 10 o'clock mass. It had been widely advertised as his farewell mass to the lay members of the Washington archdiocese.

His final message to his flock was intensely evangelistic, reflecting his deep concern during his tenure here for evangelization. He told the congregation that "human life makes no sense" without the knowledge of God, as revealed in Jesus Christ."

"Only in the truth of Jesus Christ is the identity of the human being fully disclosed," Baum said. "Be [Christ] is the way, the truth and the light."

There were no special guests from either the world of politics or religion at the service. Baum paid glowing triberation here of Christians, Jews and Muslims and to the fellowship with Christians of other denominations.

Baum, in a brillant green wool chasuble lined with cloth-of-gold conducted the service under the scrutiny of uniformed police officiers, both inside and outside of the cathedral.

The night before, 11 members of the Community for Creative Non-Violence were arrested during a demonstration in which they demanded that the cathedral be opened on winter nights to persons without shelter.

An usher confirmed that some CCNV members and the street people they serve were present at the mass, but there were no incidents.

Baum goes to Rome next week to take over the direction of the Vatican's Sacred Congregation for Catholic Education.

While speculation continues about who his successor will be for the area's 400,000 Catholics, church officials characteristically are silent on the progress being made on the choice. The selection process for a new archbishop usually takes several months, particularly in a diocese as important as this one.

Before Baum leaves, someone will be designated to administer diocesan affairs in the interim.

One source said yesterday, only partly tongue in check, that if such a person is designated an "Apostolic Administrator," it would signify a longer wait for the appointment of a new archbishop, whereas if he were simply termed "Administrator," the appointment of Baum's successor could be anticipated shortly.

Yesterday's service was also the farewell for Msgr. W. Louis Quinn, pastor of St. Matthew's, who will accompany Baum to Rome as his secretary.

Attendance at yesterday's service was relatively sparse, considering the nature of the occasion. The cathedral was two-thirds full when the mass began, although worshippers continued to drift in. Afterward, they waited in a long line to shake the cardinal's hand and have friends or family photograph the occasion.

In his homily, Baum denounced racism as "at its root a heresy" and "a denial of Christ Jesus." He concluded his remarks with a long litany of thanks, beginning with a tribute to his predecessor. Cardinal Patrick O'Boyle, who also participated in the mass.

The cardinal's parting words to the congregation were "to ask you to forgive my failures. . . and to entrust your lives always to God." He was greeted with a standing ovation.

He concluded the mass with a benediction, in Latin, which he said represented an apostolic blessing from Pope John Paul II.