Richard Viguerie, fund-raiser for the new right political coalition, told a religious forum here this week that conservative forces have a maximum of six years to move into what he called the liberal "leadership gap" and gain control of the country.

This is the opportunity for conservatives to come to power; if we don't do it now we never will," Viguerie told the Washington chapter of the Religous Public Relations Council. Pressed for a definition of "now," he said, "If we can't do it in the next six years, it's not going to happen."

According to Viguerie's analysis, liberals, who have been in the saddle for nearly half a century, are in trouble because "the liberal leaders are mostly dead or retired" and a younger generation of leaders has not moved into positions of power yet.

D.C. Del. Walter Fauntroy, who debated Viguerie before the group, supported the involvement of Christian ministers in politics but criticized the Christian right-wing for focusing on "secondary issues" instead of basic questions of "protecting the poor."

"It's all right to pray in public schools," said Fauntroy, in reference to one of the central concerns of the new evangelical right "but that's not a major issue."

In remarks laden with Biblical quotations, the Baptist clergyman warned repeatedly against following "false prophets" who are "wearing sheep's clothing, yet in their hearts are ravening wolves."

Asked about the Rev. Ralph Abernathy's recent endorsement of Ronald Reagan, Fauntroy said he was "surprised, shocked hurt and indignant." He added that he understood the "frustration" of blacks with the Carter administration, "but Mr. Reagan is not an acceptable alternative; Mr. Anderson is not a viable alternative.Therefore I am between a rock and a hard place. Because I am between a rock and a hard place, I have sense enough to take the lesser of two . . . " He caught himself before he said the word "evils."

Fauntroy was an active supporter of Sen. Edward M. Kennedy during the primaries.

Viguerie said that the ability of the new coalition of fundamentalist clergy and conservative politicians to keep together will depend "heavily on who wins the election." He predicted that the new right would be much stronger four years from now if President Carter is reelected in November. "You have problems holding together when you win," he said. "The new right couldn't get together when someone whom we perceived to be one of ours -- like Nixon or Ford -- was in office."

Viguerie identified four men as the key figures who "had the vision" to marry the drawing power of fundamentalist preachers and television evangelists with right-wing politics: Ed McAteer of the Religious Roundtable; Howard Philips of the Conservative Caucus; Paul Weyrich, director of the Committee for the Survival of a Free Congress, and the Rev. Bob Billings, a Baptist clergyman who was executive director of Moral Majority before joining the Reagan campaign.

At the conclusion of the brisk debate, the chairman of the panel commented that "God is not dead." "No sir!" Fauntroy quipped. "He's alive -- and in Lynchburg." Lynchburg, Va., is the home of the best known of the new-right preachers, the Rev. Jerry Falwell.