About 100 community, religious and political leaders met last night to discuss ways to combat what is seen as a rising tide of incidents of racial and religious hatred in Montgomery County.

"For several months we have watched as swastikas were painted on walls and crosses were burned on lawns," County Executive Charles W. Gilchrist told the meeting, convened in the county office building in Rockville.

Thirty-eight incidents, apparently motivated by racial or religious prejudice, including assaults and threats, have been reported to the Montgomery County Human Relations Commission so far this year. That compares to 25 reported in all of 1980.

Although questions have been raised whether this increase might simply reflect new willingness by victims to report such incidents, county lawmakers and black and Jewish leaders have grown increasingly concerned.

Last night Roscoe Nix, president of the county NAACP chapter, told the group that two threats were telephoned to his message recorder last week.

"Nigger, nigger, nigger, this is the klan," a voice said, according to Nix.

The second threat warned that "Montgomery County is not Niggerville," he said. Nix called for concerted education programs and efforts to arrest those responsible for such incidents."

Gilchrist said that in the past the county had withheld reaction, fearing that a highly visible stand might simply publicize hate incidents and lead to more of them. Recent events have shown it is time to act, he said.

Montgomery County police have said many incidents seem to be the work of teen-agers and do not necessarily mean that organized klan or Nazi groups are growing in strength in the county.

Two weeks ago county police arrested five teenage youths in connection with a cross burned outside the Poolsville home of a black family.

Reports from four workshops convened at last night's meeting suggested that many participants favored education in county schools to counter bigotry, publicizing hate incidents and a leadership role for county government agencies.

Attending the meeting were County Council members, Police Chief Bernard Crooke and State's Attorney Andrew Sooner. Representatives from the county's main teachers union, the Bar Association, the Board of Realtors, the AFL-CIO, the U.S. Commission on Civil Rights, Christian churches and the Jewish Community Council of Greater Washington were also present.

About 13 percent of Montgomery County's 570,000 people are Jewish and 8 percent black, according to county spokesman Charles Maier. Hispanics account for 4 percent of the population.