The National Highway Traffic Safety Administration, in a move raising the eyebrows of some civil libertarians concerned about the separation of church and state, has asked the nation's religious leaders to help promote its stepped-up campaign to get people to wear seat belts.

Along with the National Safety Council, the NHTSA is asking churches and synagogues to designate the weekend of Feb. 13-14 as "National Safety Sabbath" for all Americans to join in "a religious fellowship to rediscover the safety belt."

With $2,800 from the NHTSA, the safety council has mailed 3,000 "National Safety Sabbath" kits, complete with prayers and a special message from evangelist Billy Graham, to religious leaders across the country.

"The commandment 'Thou shalt not kill' applies to our behavior on the highways as well as to our interpersonal relationships," Graham said. "Join me in a covenant both to use safety belts and to protect children in child safety seats each time we use our cars."

To help make that covenant, the kit includes five prayers. One of them:

"O Lord, Creator, leader of all mankind . . . help me to remember that when I am in my automobile I am my brother's keeper. Let me find the daily strength to insist my fellow passengers protect themselves in safety belts when they are traveling in the car with me. Let me not waver in my obligation to insist that all infants and toddlers who ride in my car are properly secured."

Another prayer is a responsive reading in which the congregation repeatedly begins its responses, saying, "Help us to buckle up."

"Safety Sabbath" is one of a dozen efforts the NHTSA has undertaken recently to encourage Americans to wear seat belts. The campaign began several months before NHTSA head Raymond A. Peck Jr. revoked a government regulation that would have required car manufacturers to install air bags or automatic seat belts in all cars by 1984.

As part of the seat-belt campaign, the NHTSA has been trying to get television producers and advertisers to include similar messages in their shows and promotions. It has even considered getting makers of Chinese fortune cookies to include such fortunes as "Confucius say man who wear seat belt save face."

Although this is the fourth annual Safety Sabbath, this year marks the first time the NHTSA has participated in it. Until now it had been sponsored solely by the safety council.

"We didn't see any problem" with Safety Sabbath and the constitutional requirement of separation between church and state, said Edmund Pinto, director of the NHTSA's Office of Public Affairs. "An off-of-the-top-of-the-head opinion" by the NHTSA's general counsel's office concluded that the NHTSA was not violating the Constitution, Pinto said, adding, "It is not establishing any religion."

Some civil liberties experts disagree, however. Even though a small amount of money was involved, "Spending government money on this kind of promotion that is heavily religious in form and content does raise serious questions of church and state," said John Shattuck, director of the American Civil Liberties Union's Washington legislative office, after examining the Safety Sabbath kit.

"It is entirely appropriate for the government to get people to wear seat belts. But to do so in a way that pushes any general religious point of view is unappropriate under the First Amendment," he said.