The Rev. Jerry Falwell, signaling an end to a decade of highly visible political involvement, announced yesterday that he is resigning as president of the Liberty Federation and its better-known lobbying arm, the Moral Majority.

Saying his television ministry and his Lynchburg church have suffered because of his political involvement and his recent efforts to save the PTL television ministry, Falwell said, "From now on, my real platform is the pulpit, not politics."

Falwell said that, although he has endorsed Vice President Bush for president, "I will never work for a candidate again as I did for Ronald Reagan. I will not be lobbying for legislation personally, I will not be registering voters . . . . "

Jerry Nims, a board member of Falwell's television operation, the "Old Time Gospel Hour," is to replace Falwell as head of the political organizations.

An Atlanta entrepreneur and confidant of Falwell in the PTL operation, Nims said yesterday that he would like to see the organization become more involved in court cases concerning conservative issues, including prayer in public schools.

Nims and Falwell indicated that the Moral Majority will maintain a low profile in the 1988 elections, as it did in 1982 and 1986.

Falwell, who began cutting back his political activities about a year ago, said his decision had nothing to do with the Republican presidential candidacy of Marion G. (Pat) Robertson, a former television minister.

The Moral Majority, started by Falwell in June 1979, is widely credited with raising the consciousness and visibility of conservatives.

In recent years, the group has not achieved the kind of success it enjoyed in its first year with President Reagan's election in 1980.

"We're no longer breaking new ground," Falwell said on the Diane Rehm show on WAMU-FM radio yesterday. "It's no longer as glamorous to be in the religious right . . . . "

He said that the Moral Majority's monthly magazine goes to 600,000 households, that the organization maintains 6 million names on a mailing list and that revenue for fiscal 1987 was $8.4 million, $1.4 million over expenses.