Morris B. Abram, who has been an increasingly outspoken defender of the Reagan administration's civil rights policies, has resigned as vice chairman of the U.S. Commission on Civil Rights.

Abram, 67, told President Reagan he was stepping down because he wants to devote full attention to his new post as chairman of the Conference of Presidents of Major American Jewish Organizations, a coalition including the American Jewish Congress and B'nai B'rith.

The New York lawyer had been playing a more combative role on the divided civil rights commission as its chairman, Clarence M. Pendleton Jr., sought a lower profile because of controversy.

Abram, who agrees with the Justice Department that the use of racial goals and quotas is discriminatory, accused critics of trying to discredit the commission "because our ideas are unacceptable."

But Abram also came under fire for recommending two of his son's friends for commission jobs. The two men were given unusually rapid promotions, with one moving in rank from GS-7 to GS-12 in 13 months. Abram said he had nothing to do with the promotions.

As a former chairman of the United Negro College Fund and with roots in the 1960s civil rights movement, Abram was the most prestigious of Reagan's members of the commission, which spends much of its time in internal squabbles. History Lesson . . .

There was no shortage of praise in the Senate yesterday for the Finance Committee's tax-overhaul bill, which was the main order of business. Virtually every speaker commended it as "historic," citing its proposal to reduce tax rates to the lowest levels in more than a generation. But Sen. Max Baucus (D-Mont.) placed the bill's historic nature most clearly in context by observing that Congress has not written a new tax code since 1954, when "Marilyn Monroe and Joe DiMaggio were still married." -- Marjorie Williams Based on staff reports and news services