The Roman Catholic Diocese of Arlington, which governs 50 Catholic churches with 224,000 parishioners in Northern Virginia, has launched a vigorous campaign urging parents of public school students to remove their children from state-required classes in sex education.

The effort adds significant reinforcement to what has been a battle waged mostly by Protestant fundamentalists.

Ever since the Virginia General Assembly passed a law requiring so-called family life education for kindergarten through 10th grade in all public schools nearly three years ago, conservative religious groups have urged parents to fight the measure and remove their children from classes. The law included a procedure by which parents can hold their children out of the classes.

The diocesan Office for Family Life in Arlington has dispatched volunteer speakers to about 15 Catholic parishes so far, accompanied by videotapes and literature prepared by citizen and church groups.

The issue has been covered in the diocesan newspaper, which goes to more than 36,000 Northern Virginia homes. In addition, thousands of Catholic parents have received from the church copies of forms they can file with their public school districts removing their children from sex education classes.

A spokesman for Arlington Bishop John R. Keating said that the effort is not sanctioned by Keating, but that the bishop has not tried to stop it.

Paul O'Brien, a lay volunteer for the diocesan Office of Family Life and a frequent speaker before parent groups, criticizes Virginia's sex education program for an absence of "moral values."

"It gives {students} bad options that some have never thought of," he said in an interview. "You'll never see the word 'obey' your parents."

The number of parents who remove their children from sex education classes ranges from about 2 percent to 6 percent among area school systems and remains stable, school officials say.

But the Catholics' entrance into the education controversy is viewed as significant by family life education proponents in Fairfax and Arlington counties, where most of the activity is centered.

The Catholic parish structure provides a ready network to reach tens of thousands of parents, said Jerald L. Newberry, hired by Fairfax County to work with the community on the issue of family life education.

A letter sent to 1,200 Catholic families from St. Ambrose Church in Annandale by the pastor, the Rev. Mark Pilon, warned parents that the Fairfax program "will introduce your 7th graders (11/12 year-olds), by means of the most explicit graphics, to virtually every possible form of sexual activity, heterosexual or homosexual, moral or immoral."

But according to Newberry, "There is no reference to homosexuality in {Fairfax County's} seventh- or eighth-grade curriculum. There are no graphics regarding sexual activity in any {family life education} lesson at any grade level."

Pilon said the part of his letter on the seventh grade was erroneous, but he said he stood by the rest of it.

Those who have long fought sex education say they welcome the church's efforts.

"They've done an awful lot of education, even more than the Protestant churches. They've done a good job and a needed job," said Roland Biser, vice president of the Fairfax Citizens' Council, a conservative political group.

Family life education, which is being introduced this year in all 132 Virginia school districts, includes instruction not only on contraception and sexually transmitted diseases, but also on decision-making, assertiveness, and tolerance.

Although most Virginia districts, including all those in Northern Virginia, have written their own curriculums, the programs share a philosophy that students who learn to think for themselves are more likely to say "no" to dangerous behavior than are students who have been lectured about absolute right and wrong, according to teachers who have developed the programs.

NUMBER CHOOSING NOT TO ATTEND FAMILY LIFE CLASSES

IN GRADES K-10 IN NORTHERN VIRGINIA

Jurisdiction................Total Enrollment......% Opting Out

Alexandria.............................9,488............6-8.0%

Arlington County......................14,815..............0.5

Falls Church...........................1,224..............2.0

Fairfax County.......................129,612.........1.30-2.38

Loudoun County........................14,632..............4.9

Prince William County.................41,353..............1.34

SOURCE: Area Schools