Virginia's Charles S. Robb -- cast as the gubernatorial candidate of an unnamed political party, running against an anonymous opponent -- made his advertising debut tonight during a break in the popular TV show, "Real People."

The $100,000 ad campaign of the Democratic nominee for governor unveils a slogan, "For a Future Worthy of Her Past." But unlike the earlier, costlier commercial blitz of his campaign foe, Republican J. Marshall Coleman, Robb's ads do not mention his opponent's name.

They also neglect to spell out Robb's party affiliation. Robb aide George Stoddart, who had not seen the commercials as of this afternoon, said he was unable to explain why Robb is not identified as a Democrat. "But I'm sure Squier knows what he's doing," he said, in a reference to Robb's Washington-based media consultant, Robert Squier.

Robb's election as lieutenant governor in 1977 is one of the few times in the last dozen years that a member of his party has won a statewide race. Although Democrats outnumber Republicans 3 to 1 in the state legislature, Republicans have controlled the governorship since 1969. Coleman holds the office of attorney general. The GOP also controls nine of the state's 10 congressional seats.

The series of six commercials -- two of them 60 seconds in length and four of 30-second duration -- will be shown through July 1 on stations in Washington, Richmond, Norfolk, Roanoke and Lynchburg.

They depict Robb as he is, serious, formal and always wearing a tie, in settings that range from a Clark County dairy farm to a home construction site in McLean.

One was filmed as Fairfax County's Mount Vernon High School, from which Robb graduated 25 years ago. In that ad, Robb bemoans that Virginia has slipped from 24th to 39th among the states in education, although he does not say on what basis the ranking was made. He also appears to contradict the decline by telling the students that as a student there in the late 1950s, he "didn't have facilities that even approach this."

Other subjects of the Robb commercials are agriculture, tourism and economic development.

None is likely to set Robb far apart from Coleman, although Robb's approach to the sagging building trades industry, the topic of two of his commercials, is the subject of a continuing tempest in an otherwise unboiling teapot. At a press conference at the state capitol today, Coleman denounced as "social engineering" and "fiscal gimmickry" Robb's suggestion that up to 20 percent of state employes' retirement funds be invested in home mortgages.

In what was effectively a warm-up for a 90-minute debate, to be televised Friday over the state's educational television network (9 p.m., Channel 53/14), Coleman said Robb made "a grave mistake in suggesting he would impose this [plan]" on the state board that administers the retirement funds.

Moments later, on the lawn outside the State House, Robb said he had "not changed one iota" about the idea, but conceded that his suggestion, made 10 days ago to a convention of savings and loan officials, "might have been misleading."

He is not talking about "forcing" the fund to invest in home mortgages, Robb said, but as governor he would provide "leadership and persuasion" in urging the trustees to consider it. Robb said he would also favor legislation that would permit increasing the limit of pension funds that could be invested in mortgages from 20 percent to 35 percent.

In one of the commercials about the home-building industry, a bricklayer tells Robb that for the first time in 30 years he is going to be forced to lay off his crew. Robb responds that "if we don't find the solution, some good, hard-working people will go under."

In another commercial, Robb climbs a ladder on the shell of a house and then says that "government, business and labor must not be an adversary process, we've got to get together." He adds that his much talked-about but little-read economic development plan is "designed to meet these problems head-on."

Coleman launched a $250,000 advertising campaign on May 9 that, in contrast to Robb's commercials, stressed Coleman's Republicanism and gave Robb's name equal billing.

Doug Bailey of the McLean-based firm of Bailey, Deardourff Associates, which produced the Coleman ads, said the early start was designed to help Coleman catch up with Robb in name recognition. Bailey acknowledged that Robb was ahead in that category by virtue of being the son-in-law of the late President Lyndon B. Johnson.

Coleman's commercials, which went off the air about three weeks ago, linked him with the popularity of President Reagan and by inference, attempted to saddle Robb with the policies of former president Carter