"What do Jerry Falwell, the John Birch Society and Stan Parris have in common?"

According to radio spots by Richard L. Saslaw, the Virginia Democrat who is trying to unseat Rep. Parris this fall, quite a bit.

"Stan Parris and Jerry Falwell are opposed to a nuclear freeze, so is the John Birch Society," say the Saslaw ads. "Stan Parris and Jerry Falwell are opposed to the Voting Rights Act, so is the John Birch Society . . . . It's no wonder the John Birch Society has given Parris an 80 percent approval rating."

The ads, among the most negative that have aired in Northern Virginia this fall, "are the mark of a desperate campaign," said Dick Leggitt, a Parris spokesman. He was referring to the Birch ad, which ran last week over area radio stations, and another Saslaw ad running this week in which "George Washington" links Parris to King George III.

The advertisements are part of a new hard-hitting package of radio spots produced for the Saslaw campaign by Gerald Austin Associates, a political consulting firm in Columbus, Ohio.

"We're focusing on Parris and informing people that while Stan Parris is a nice guy, his voting record is more right-wing," said Joe Gleason, a Saslaw campaign spokesman.

With less than three weeks left in the congressional races, Democrats also are hoping that the $15,000-a-week advertising campaign will attract attention and money to Saslaw, whose race has been languishing, according to many Democrats.

Parris, who is seeking his third consecutive term in the House of Representatives, reported this week that he had raised $500,000 more than Saslaw and has said he will spend time campaigning outside the normally volatile district, which he won by about 1,000 votes in 1982.

This week's Saslaw radio spot starts out with the strains of "Yankee Doodle."

"Hello, this is your old friend, George Washington," says a voice, adding that the Saslaw-Parris race is a "real humdinger." He criticizes Parris for opposing the Voting Rights Act, and says that Parris has refused to debate, unless audience questions are banned.

"Old King George would have loved Stan Parris . . . . Stanford, if we didn't allow folks to ask questions, we'd be singing "God Save the Queen" instead of the "Star Spangled Banner."

"It's interesting . . . but it takes a great deal of liberty with the facts," said Leggitt.

He predicted the radio spots would backfire. "To imply that Congressman Parris, who voted for the ERA and who voted for the Martin Luther King holiday bill, is somehow in the hip pocket of an ultra-right organization would not appear to withstand the scrutiny of an intelligent observer," he said, adding that 143 congressmen have higher ratings from the conservative John Birch Society than Parris.

"My understanding is that they have pulled those ads the John Birch Society radio spots because they were besieged with complaints," Leggitt said.

A Saslaw campaign official denied that, saying the ads have been very successful and the original plan was to run the John Birch Society spot for only one week. "If it's getting them that upset, we might toughen it up and run it again," said Paul Krell, the Saslaw manager.

Saslaw spokesman Joe Gleason said their polls show that Parris is much more conservative than most voters in the 8th District, which includes Alexandria, southern Fairfax, eastern Prince William and northern Stafford counties.

Gleason agreed that the intent of the ads is to link Parris with the radical conservative elements of the Republican Party. "You look at his voting . . . on equal rights amendments, the Voting Rights Act, it's pretty right-wing."

Not so, says Leggitt. "They just don't want to let facts get in the way of a good commercial."