U.S. District Court Judge Charles R. Richey, citing constitutional guarantees of freedom of religion, has dismissed charges of illegal camping against five members of Lafayette Park's round-the-clock band of peace demonstrators.

"I think the ruling shows there is hope for civilization," said William Thomas, 39, a former truck driver and jewelry maker and self-described former heroin addict, who said he has conducted a continuous peace vigil since 1981 in Lafayette Park and on the White House sidewalk across Pennsylvania Avenue.

"Judge Richey is what law is all about," Thomas declared yesterday as he stood with his disarmament signs on the park's rainy brick sidewalk. Thomas said he would continue the protest indefinitely, even though he has been arrested "dozens of times" for violating National Park Service regulations. He said he has been convicted only twice and received suspended sentences.

On Thursday, Richey dismissed charges against Thomas, his wife Ellen and three other persons of violating a Park Service ban against camping in the park. The five were arrested about 2:30 a.m. on Dec. 22.

In a three-page order, Richey said the government did not dispute the demonstrators' claim that they were acting because of "sincerely held religious belief." Therefore, Richey said, authorities could enforce the regulation only if they showed a "compelling interest" in upholding it and did so "with the least restrictive means with respect to that religious belief."

"The government did not offer a scintilla of evidence to that effect," Richey declared.

A spokesman for U.S. Attorney Joseph E. diGenova declined to say whether the ruling would be appealed or whether U.S. Park Police would continue to try to enforce the regulation. Under court rules, the decision is not binding on other judges.

In 1984 the Supreme Court upheld the government ban on overnight camping in the park, ruling that it did not violate the constitutional guarantee of free speech contained in the First Amendment.

Thomas, who represented himself in the new case, said this was the first time he had challenged an arrest on the basis of the freedom of religion clause of the same amendment.

But the skirmishing in the park appears far from over.

Yesterday afternoon Stephen (Sunrise) Semple, 27, whose charges had been dismissed by Richey along with those of Thomas, was arraigned by a U.S. magistrate on charges of violating the camping ban again on Dec. 27 and Dec. 28. Semple said he pleaded not guilty and asked that his case be tried by a federal judge.

Ellen Thomas, 39, a former paralegal who met her husband while both were demonstrating in the park, was also arraigned yesterday on charges of leaving her signs unattended on Jan. 8.

The others against whom the Dec. 22 charges were dismissed are Phillip Joseph and Scott M. Galindez. Joseph is spending five days in D.C. Jail for failing to appear in D.C. Superior Court on another charge of violating park demonstration rules. Thomas said Galindez, who told police his home was in Albany, N.Y., left Lafayette Park two weeks ago after spending about six months there. Galindez did not appear at the hearing at which the charges against him were dismissed.

Meanwhile, five demonstrators with antinuclear signs were in the park last evening, several of them lying on the sidewalk under large sheets of plastic. Thomas said they would stay there again all night.